diff --git a/nifty5/dobj.py b/nifty5/dobj.py
index 5a5ae948d800841ff6cd0e058e95430e544068c1..bdbc265c136fa5cd16b37f10c337ef9dba93aca0 100644
--- a/nifty5/dobj.py
+++ b/nifty5/dobj.py
@@ -17,8 +17,8 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from .compat import *
 
+from .compat import *
 
 try:
     from mpi4py import MPI
diff --git a/nifty5/domain_tuple.py b/nifty5/domain_tuple.py
index e12cab393950bcdee636bd895be0bdf0db5a8597..efc9c2418d608c40ac7ea0b0dbcf160f364e3445 100644
--- a/nifty5/domain_tuple.py
+++ b/nifty5/domain_tuple.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from .compat import *
 from .domains.domain import Domain
 
diff --git a/nifty5/field.py b/nifty5/field.py
index 6aef77c2a99bc999c3888ec0767de9a9a3d5edb1..d331f7444fb336bbda1a51299ece09863e696a97 100644
--- a/nifty5/field.py
+++ b/nifty5/field.py
@@ -17,11 +17,12 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from .compat import *
+
 import numpy as np
-from . import utilities
+
+from . import dobj, utilities
+from .compat import *
 from .domain_tuple import DomainTuple
-from . import dobj
 
 
 class Field(object):
diff --git a/nifty5/logger.py b/nifty5/logger.py
index 9636970f68c8c19b274bc279e8473c50718e1c60..07da465894f482f93cfaac3e858096dbaed020cd 100644
--- a/nifty5/logger.py
+++ b/nifty5/logger.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from .compat import *
 
 
diff --git a/nifty5/minimization/conjugate_gradient.py b/nifty5/minimization/conjugate_gradient.py
index 5974d226b0cb9aaad6fcfc6ab7c5d63b7158bf13..9a621917c4234c2bd8f0aa30d2a55f09e39728c8 100644
--- a/nifty5/minimization/conjugate_gradient.py
+++ b/nifty5/minimization/conjugate_gradient.py
@@ -17,9 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
-from .minimizer import Minimizer
 from ..logger import logger
+from .minimizer import Minimizer
 
 
 class ConjugateGradient(Minimizer):
diff --git a/nifty5/minimization/descent_minimizer.py b/nifty5/minimization/descent_minimizer.py
index eae2e783b8451f398596acddd1c28a3e5642f4f0..b0d3663f852a8496a4f48eb9d231e8addcc556e2 100644
--- a/nifty5/minimization/descent_minimizer.py
+++ b/nifty5/minimization/descent_minimizer.py
@@ -17,11 +17,13 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import abc
-from .minimizer import Minimizer
-from .line_search_strong_wolfe import LineSearchStrongWolfe
+
+from ..compat import *
 from ..logger import logger
+from .line_search_strong_wolfe import LineSearchStrongWolfe
+from .minimizer import Minimizer
 
 
 class DescentMinimizer(Minimizer):
diff --git a/nifty5/minimization/energy.py b/nifty5/minimization/energy.py
index f567a0e38cee4f29dc51f2141d2bf2de7b5ce268..847e40827cf64fd2001372612f5282872ae465a4 100644
--- a/nifty5/minimization/energy.py
+++ b/nifty5/minimization/energy.py
@@ -17,9 +17,8 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
-import numpy as np
-from ..field import Field
 from ..utilities import NiftyMetaBase, memo
 
 
diff --git a/nifty5/minimization/energy_sum.py b/nifty5/minimization/energy_sum.py
index 02d9d88250a4909b89326971d3ce2a4f48c47149..de8d593089df065358d141074b22f51d13ca4644 100644
--- a/nifty5/minimization/energy_sum.py
+++ b/nifty5/minimization/energy_sum.py
@@ -17,8 +17,9 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
-from ..utilities import memo, my_lincomb_simple, my_lincomb
+from ..utilities import memo, my_lincomb, my_lincomb_simple
 from .energy import Energy
 
 
diff --git a/nifty5/minimization/gradient_norm_controller.py b/nifty5/minimization/gradient_norm_controller.py
index b17dba54beb43eb2168588a882e2ef79a60fa237..c7d98be961ea5adc4e10343b71e375017b13ae7a 100644
--- a/nifty5/minimization/gradient_norm_controller.py
+++ b/nifty5/minimization/gradient_norm_controller.py
@@ -17,9 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
-from .iteration_controller import IterationController
 from ..logger import logger
+from .iteration_controller import IterationController
 
 
 class GradientNormController(IterationController):
diff --git a/nifty5/minimization/iteration_controller.py b/nifty5/minimization/iteration_controller.py
index b060287513ac1850d829df4393893efd99a0a0e5..6d9f95bc621d43ad5c9b2dee29c7c167b36e86ed 100644
--- a/nifty5/minimization/iteration_controller.py
+++ b/nifty5/minimization/iteration_controller.py
@@ -17,8 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import abc
+
+from ..compat import *
 from ..utilities import NiftyMetaBase
 
 
diff --git a/nifty5/minimization/l_bfgs.py b/nifty5/minimization/l_bfgs.py
index a31a556394e8ddaf505a2cdd1c1725294b6fe58f..ed289a356a8fd62ad3d93a41ad4b0b8d1d0136c5 100644
--- a/nifty5/minimization/l_bfgs.py
+++ b/nifty5/minimization/l_bfgs.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from ..logger import logger
 from .descent_minimizer import DescentMinimizer
diff --git a/nifty5/minimization/line_energy.py b/nifty5/minimization/line_energy.py
index bb7ccb0d13a42d4876346578cb696899f9e786e4..f6fd528d2da8e514d29915719e762a5ed083ad08 100644
--- a/nifty5/minimization/line_energy.py
+++ b/nifty5/minimization/line_energy.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 
 
diff --git a/nifty5/minimization/line_search.py b/nifty5/minimization/line_search.py
index 0e77f26a6fad147fc68a18a56c795f7b41625b7a..d569868c7f934d4cf57402735c279cd0a196a09c 100644
--- a/nifty5/minimization/line_search.py
+++ b/nifty5/minimization/line_search.py
@@ -17,8 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import abc
+
+from ..compat import *
 from ..utilities import NiftyMetaBase
 
 
diff --git a/nifty5/minimization/line_search_strong_wolfe.py b/nifty5/minimization/line_search_strong_wolfe.py
index 1960300ebbc4f94afa4a09a6f35d15afc6127841..0ab929abf8e56254ec537929e38c3786e8897434 100644
--- a/nifty5/minimization/line_search_strong_wolfe.py
+++ b/nifty5/minimization/line_search_strong_wolfe.py
@@ -17,11 +17,13 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
-from .line_search import LineSearch
-from .line_energy import LineEnergy
+
+from ..compat import *
 from ..logger import logger
+from .line_energy import LineEnergy
+from .line_search import LineSearch
 
 
 class LineSearchStrongWolfe(LineSearch):
diff --git a/nifty5/minimization/minimizer.py b/nifty5/minimization/minimizer.py
index 89058659ec125bffe409c27621452a1ee58eabc2..6f8bd038ec1f23d5416925750513e38057d472bf 100644
--- a/nifty5/minimization/minimizer.py
+++ b/nifty5/minimization/minimizer.py
@@ -17,8 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import abc
+
+from ..compat import *
 from ..utilities import NiftyMetaBase
 
 
diff --git a/nifty5/minimization/nonlinear_cg.py b/nifty5/minimization/nonlinear_cg.py
index b2db3f72698172d5b2cc6e824a1347d8ef24fe2d..426d3ba4acb3d046b1b553080a57e6a4ae6fe9f5 100644
--- a/nifty5/minimization/nonlinear_cg.py
+++ b/nifty5/minimization/nonlinear_cg.py
@@ -17,9 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
-from .minimizer import Minimizer
 from .line_search_strong_wolfe import LineSearchStrongWolfe
+from .minimizer import Minimizer
 
 
 class NonlinearCG(Minimizer):
diff --git a/nifty5/minimization/quadratic_energy.py b/nifty5/minimization/quadratic_energy.py
index 9e27257e6df82e6e16cf37a66622b38763ef5935..b6931e6e18a67a11a8bc8a70fd25c7f66e452e78 100644
--- a/nifty5/minimization/quadratic_energy.py
+++ b/nifty5/minimization/quadratic_energy.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from .energy import Energy
 
diff --git a/nifty5/minimization/relaxed_newton.py b/nifty5/minimization/relaxed_newton.py
index c8dd59d611ec01f27d6f51c540a5efde9cff592b..df07e57ba404b341c33532397b55328c7bd0b9ef 100644
--- a/nifty5/minimization/relaxed_newton.py
+++ b/nifty5/minimization/relaxed_newton.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from .descent_minimizer import DescentMinimizer
 from .line_search_strong_wolfe import LineSearchStrongWolfe
diff --git a/nifty5/minimization/scipy_minimizer.py b/nifty5/minimization/scipy_minimizer.py
index ed028f74db96034c60b1bcfb2bd0f259de26138c..7cc3830d2d1518282d4ed08da6709cf47171d0c9 100644
--- a/nifty5/minimization/scipy_minimizer.py
+++ b/nifty5/minimization/scipy_minimizer.py
@@ -17,12 +17,13 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
+from .. import dobj
 from ..compat import *
-from .minimizer import Minimizer
 from ..field import Field
-from .. import dobj
 from ..logger import logger
 from .iteration_controller import IterationController
+from .minimizer import Minimizer
 
 
 def _toNdarray(fld):
diff --git a/nifty5/minimization/steepest_descent.py b/nifty5/minimization/steepest_descent.py
index 77a56436e47e5f257e77edd7e74d49802d14464e..22ebb51149c68ee5244068e7be41747ece22f1f9 100644
--- a/nifty5/minimization/steepest_descent.py
+++ b/nifty5/minimization/steepest_descent.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from .descent_minimizer import DescentMinimizer
 
diff --git a/nifty5/minimization/vl_bfgs.py b/nifty5/minimization/vl_bfgs.py
index 9822b4c23c9863d318897321508cf896e049854b..3144e84bb8588e77dea7fa9c351f8e0cd2124484 100644
--- a/nifty5/minimization/vl_bfgs.py
+++ b/nifty5/minimization/vl_bfgs.py
@@ -17,8 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
+
+from ..compat import *
 from .descent_minimizer import DescentMinimizer
 from .line_search_strong_wolfe import LineSearchStrongWolfe
 
diff --git a/nifty5/models/binary_helpers.py b/nifty5/models/binary_helpers.py
index a778f152f65ec0af13477f5edc1f8571c062dfa3..645535b1f6f6d29ee915cb215e62a450253790bb 100644
--- a/nifty5/models/binary_helpers.py
+++ b/nifty5/models/binary_helpers.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from ..multi.multi_field import MultiField
 from ..sugar import makeOp
diff --git a/nifty5/models/constant.py b/nifty5/models/constant.py
index 3a044d8809e5bfa79d2e6bf1e06e3475d44a42f7..1241653b1dc3a2dd1c8a3b11641ae5a1cc53c2ce 100644
--- a/nifty5/models/constant.py
+++ b/nifty5/models/constant.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from .model import Model
 
diff --git a/nifty5/models/linear_model.py b/nifty5/models/linear_model.py
index b0ff0f3c05d738bb1412893c95c00e0ba1cb5b3a..479b84896a5668f8bcde3da0ddd6d0a6073e4ade 100644
--- a/nifty5/models/linear_model.py
+++ b/nifty5/models/linear_model.py
@@ -16,6 +16,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from ..operators.selection_operator import SelectionOperator
 from .model import Model
diff --git a/nifty5/models/local_nonlinearity.py b/nifty5/models/local_nonlinearity.py
index 02605dfa1f187e727f50d32281ea1d88cda9ca52..e9e03a57aa34d87f5373d4b85a8c462d607379d7 100644
--- a/nifty5/models/local_nonlinearity.py
+++ b/nifty5/models/local_nonlinearity.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from ..nonlinearities import Exponential, PositiveTanh, Tanh
 from ..sugar import makeOp
diff --git a/nifty5/models/model.py b/nifty5/models/model.py
index 5ab8623100fba6ddad0125695902938746c1cb2f..74076f750f3680c9493648301d0a71eb4e49354f 100644
--- a/nifty5/models/model.py
+++ b/nifty5/models/model.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from ..field import Field
 from ..multi.multi_field import MultiField
diff --git a/nifty5/models/multi_model.py b/nifty5/models/multi_model.py
index 2033923daf852ac0ddc4342b8b219843674835fa..3a10f351c760941df87768337672e67b545759e7 100644
--- a/nifty5/models/multi_model.py
+++ b/nifty5/models/multi_model.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from ..domain_tuple import DomainTuple
 from ..multi.multi_field import MultiField
diff --git a/nifty5/models/variable.py b/nifty5/models/variable.py
index 3937f6dff996d9f4806f7e1f92bcb03602b9c430..86179bcd314f1d3a32a5e3aa94fbe3639626db68 100644
--- a/nifty5/models/variable.py
+++ b/nifty5/models/variable.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from ..operators.scaling_operator import ScalingOperator
 from .model import Model
diff --git a/nifty5/multi/block_diagonal_operator.py b/nifty5/multi/block_diagonal_operator.py
index 613da1d89055d5d92f2c4caa77808cf5796c1ddb..ed200ca7da657f9586b6afa0dcdfd14a5e3163a0 100644
--- a/nifty5/multi/block_diagonal_operator.py
+++ b/nifty5/multi/block_diagonal_operator.py
@@ -17,10 +17,9 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
-import numpy as np
 from ..operators.endomorphic_operator import EndomorphicOperator
-from .multi_domain import MultiDomain
 from .multi_field import MultiField
 
 
diff --git a/nifty5/multi/multi_domain.py b/nifty5/multi/multi_domain.py
index 15d22fa59c75a13382cc9ea5edde52a190d7c459..d0d6e977ad5188ea5985f87abdf909aa4e0ad483 100644
--- a/nifty5/multi/multi_domain.py
+++ b/nifty5/multi/multi_domain.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from ..domain_tuple import DomainTuple
 from ..utilities import frozendict
diff --git a/nifty5/multi/multi_field.py b/nifty5/multi/multi_field.py
index 8d99e6cbeb75e4b1faa9a818db88fb9b48d9b004..4a7217f3fdb41ca6bf6e521c3a48f4fc763ce87b 100644
--- a/nifty5/multi/multi_field.py
+++ b/nifty5/multi/multi_field.py
@@ -17,11 +17,12 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
+import numpy as np
+
 from ..compat import *
 from ..field import Field
-import numpy as np
 from .multi_domain import MultiDomain
-from ..utilities import frozendict
 
 
 class MultiField(object):
diff --git a/nifty5/nonlinearities.py b/nifty5/nonlinearities.py
index 7dff83349f0acc1cc69d7c3833d9760cc2cf4b2a..87004f2a3fbb24b4bb4de6e0c3e7542a26cf318f 100644
--- a/nifty5/nonlinearities.py
+++ b/nifty5/nonlinearities.py
@@ -17,8 +17,9 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from .compat import *
-from .sugar import full, exp, tanh
+from .sugar import exp, full, tanh
 
 
 class Linear(object):
diff --git a/nifty5/operators/chain_operator.py b/nifty5/operators/chain_operator.py
index 40f6d844c93b7f22800373262433a6d6bfafa632..efde7d8251a5cdcb8dd4f5f6dd8c736b84958763 100644
--- a/nifty5/operators/chain_operator.py
+++ b/nifty5/operators/chain_operator.py
@@ -17,8 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
+
+from ..compat import *
 from .linear_operator import LinearOperator
 
 
diff --git a/nifty5/operators/diagonal_operator.py b/nifty5/operators/diagonal_operator.py
index cf0b3810b06d7b15ddff7dfc8e3bb5011c976476..3f88e3b6f2f8b228bfe62a91d3dfbd7bc002926e 100644
--- a/nifty5/operators/diagonal_operator.py
+++ b/nifty5/operators/diagonal_operator.py
@@ -17,13 +17,14 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
-from ..field import Field
+
+from .. import dobj, utilities
+from ..compat import *
 from ..domain_tuple import DomainTuple
+from ..field import Field
 from .endomorphic_operator import EndomorphicOperator
-from .. import utilities
-from .. import dobj
 
 
 class DiagonalOperator(EndomorphicOperator):
diff --git a/nifty5/operators/dof_distributor.py b/nifty5/operators/dof_distributor.py
index efcace429cc3e6863f1141290cf0c83c25d8142c..44f2e472b40a7b8658fe6231d2dd05cd2abb0cd6 100644
--- a/nifty5/operators/dof_distributor.py
+++ b/nifty5/operators/dof_distributor.py
@@ -17,14 +17,16 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
-from .linear_operator import LinearOperator
-from ..utilities import infer_space
-from ..field import Field
-from ..domain_tuple import DomainTuple
+
 from .. import dobj
+from ..compat import *
+from ..domain_tuple import DomainTuple
 from ..domains.dof_space import DOFSpace
+from ..field import Field
+from ..utilities import infer_space
+from .linear_operator import LinearOperator
 
 
 class DOFDistributor(LinearOperator):
diff --git a/nifty5/operators/domain_distributor.py b/nifty5/operators/domain_distributor.py
index 3bc53ea46f91e5c8a72a7cb38fb088edf22b8f2c..622214c480cd7f71ca2d6b9775980ceefd6e8c62 100644
--- a/nifty5/operators/domain_distributor.py
+++ b/nifty5/operators/domain_distributor.py
@@ -17,11 +17,13 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
-from ..field import Field
+
 from .. import dobj
+from ..compat import *
 from ..domain_tuple import DomainTuple
+from ..field import Field
 from .linear_operator import LinearOperator
 
 
diff --git a/nifty5/operators/endomorphic_operator.py b/nifty5/operators/endomorphic_operator.py
index 39edb7b2907fa273fb88f7b7d35c00ad9a6a7de1..081742441469adba67e2150a2e51fc5cd30662e1 100644
--- a/nifty5/operators/endomorphic_operator.py
+++ b/nifty5/operators/endomorphic_operator.py
@@ -17,9 +17,11 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
+import numpy as np
+
 from ..compat import *
 from .linear_operator import LinearOperator
-import numpy as np
 
 
 class EndomorphicOperator(LinearOperator):
diff --git a/nifty5/operators/exp_transform.py b/nifty5/operators/exp_transform.py
index 66a05a1e3356d7cf7e828385d3bfd3cae4d4ae93..522c54687ee5077e20236a9d1f6398cdc70dd932 100644
--- a/nifty5/operators/exp_transform.py
+++ b/nifty5/operators/exp_transform.py
@@ -17,14 +17,16 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
+
+from .. import dobj
+from ..compat import *
 from ..domain_tuple import DomainTuple
 from ..domains.power_space import PowerSpace
 from ..domains.rg_space import RGSpace
 from ..field import Field
 from .linear_operator import LinearOperator
-from .. import dobj
 
 
 class ExpTransform(LinearOperator):
diff --git a/nifty5/operators/fft_operator.py b/nifty5/operators/fft_operator.py
index 5fa35e40a40a6624c0ad0dca04464340c463c478..c96687005c1c39f5dcca19066c37bfdd28616b7f 100644
--- a/nifty5/operators/fft_operator.py
+++ b/nifty5/operators/fft_operator.py
@@ -17,14 +17,15 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
+
+from .. import dobj, utilities
+from ..compat import *
 from ..domain_tuple import DomainTuple
 from ..domains.rg_space import RGSpace
-from .linear_operator import LinearOperator
-from .. import dobj
-from .. import utilities
 from ..field import Field
+from .linear_operator import LinearOperator
 
 
 class FFTOperator(LinearOperator):
diff --git a/nifty5/operators/fft_smoothing_operator.py b/nifty5/operators/fft_smoothing_operator.py
index 08fce06bea00b94aeffe436e1e61f7afe6294e13..c849a471f441e572e095401676e3b6d43168c942 100644
--- a/nifty5/operators/fft_smoothing_operator.py
+++ b/nifty5/operators/fft_smoothing_operator.py
@@ -17,12 +17,13 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
-from .scaling_operator import ScalingOperator
-from .fft_operator import FFTOperator
+from ..domain_tuple import DomainTuple
 from ..utilities import infer_space
 from .diagonal_operator import DiagonalOperator
-from ..domain_tuple import DomainTuple
+from .fft_operator import FFTOperator
+from .scaling_operator import ScalingOperator
 
 
 def FFTSmoothingOperator(domain, sigma, space=None):
diff --git a/nifty5/operators/geometry_remover.py b/nifty5/operators/geometry_remover.py
index 67567ddb1c1616355e4886adf466fde91d31481c..6daf88fab5b8eb211dad39876b9f8bbed88bbe4d 100644
--- a/nifty5/operators/geometry_remover.py
+++ b/nifty5/operators/geometry_remover.py
@@ -17,9 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
-from ..domains.unstructured_domain import UnstructuredDomain
 from ..domain_tuple import DomainTuple
+from ..domains.unstructured_domain import UnstructuredDomain
 from .linear_operator import LinearOperator
 
 
diff --git a/nifty5/operators/harmonic_transform_operator.py b/nifty5/operators/harmonic_transform_operator.py
index 8c984f0f11e7f41f04e06cfbeb258fd85cb0fee4..9233ac5dd1b325450a437cda1528b1f8fed2e72b 100644
--- a/nifty5/operators/harmonic_transform_operator.py
+++ b/nifty5/operators/harmonic_transform_operator.py
@@ -17,13 +17,14 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
+from .. import utilities
 from ..compat import *
 from ..domain_tuple import DomainTuple
 from ..domains.rg_space import RGSpace
-from .linear_operator import LinearOperator
 from .fft_operator import FFTOperator
+from .linear_operator import LinearOperator
 from .sht_operator import SHTOperator
-from .. import utilities
 
 
 class HarmonicTransformOperator(LinearOperator):
diff --git a/nifty5/operators/inversion_enabler.py b/nifty5/operators/inversion_enabler.py
index f612eeeb07f9e8b8fac2717fcee0289ea2549282..ba9fff48a83dc2b61ff11d704080311542afba32 100644
--- a/nifty5/operators/inversion_enabler.py
+++ b/nifty5/operators/inversion_enabler.py
@@ -17,14 +17,16 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
+
+from ..compat import *
 from ..logger import logger
 from ..minimization.conjugate_gradient import ConjugateGradient
 from ..minimization.iteration_controller import IterationController
 from ..minimization.quadratic_energy import QuadraticEnergy
-from .endomorphic_operator import EndomorphicOperator
 from ..sugar import full
+from .endomorphic_operator import EndomorphicOperator
 
 
 class InversionEnabler(EndomorphicOperator):
diff --git a/nifty5/operators/laplace_operator.py b/nifty5/operators/laplace_operator.py
index 6ed7aa7c91cd4b190759ccbe01ba03cc3c911880..0725d8ea3f39368ef68c83d9e625f3dea64822e9 100644
--- a/nifty5/operators/laplace_operator.py
+++ b/nifty5/operators/laplace_operator.py
@@ -17,14 +17,16 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
-from ..field import Field
+
+from .. import dobj
+from ..compat import *
+from ..domain_tuple import DomainTuple
 from ..domains.power_space import PowerSpace
-from .endomorphic_operator import EndomorphicOperator
+from ..field import Field
 from ..utilities import infer_space
-from ..domain_tuple import DomainTuple
-from .. import dobj
+from .endomorphic_operator import EndomorphicOperator
 
 
 class LaplaceOperator(EndomorphicOperator):
diff --git a/nifty5/operators/linear_operator.py b/nifty5/operators/linear_operator.py
index 34f4d3d099ae41c4b7a73ce6fb59a93d2d2080d9..233573f27763fabd9bb1bc65639566b20a772ea5 100644
--- a/nifty5/operators/linear_operator.py
+++ b/nifty5/operators/linear_operator.py
@@ -17,9 +17,12 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import abc
+
 import numpy as np
+
+from ..compat import *
 from ..utilities import NiftyMetaBase
 
 
diff --git a/nifty5/operators/mask_operator.py b/nifty5/operators/mask_operator.py
index a9b39e8ce9bb6790e230f07d95a87755df50616f..84b15e3cb35f0856c2e03c1e14fd7a0613303309 100644
--- a/nifty5/operators/mask_operator.py
+++ b/nifty5/operators/mask_operator.py
@@ -17,8 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
+
+from ..compat import *
 from ..domain_tuple import DomainTuple
 from ..domains.unstructured_domain import UnstructuredDomain
 from ..field import Field
diff --git a/nifty5/operators/multi_adaptor.py b/nifty5/operators/multi_adaptor.py
index 50cbfbc2ea566c7951de5804363ee80bf73fbbd8..bfe712d78200a04e9a5385abd80ab04e5dce75c0 100644
--- a/nifty5/operators/multi_adaptor.py
+++ b/nifty5/operators/multi_adaptor.py
@@ -17,8 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from ..multi.multi_domain import MultiDomain
+from .selection_operator import SelectionOperator
 
 
 def MultiAdaptor(target):
diff --git a/nifty5/operators/operator_adapter.py b/nifty5/operators/operator_adapter.py
index 678ce58afc36793e16ec2bb4202a985028b1b971..310a56b66d7114da2071209156da92f11f64f7bd 100644
--- a/nifty5/operators/operator_adapter.py
+++ b/nifty5/operators/operator_adapter.py
@@ -17,9 +17,11 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
+import numpy as np
+
 from ..compat import *
 from .linear_operator import LinearOperator
-import numpy as np
 
 
 class OperatorAdapter(LinearOperator):
diff --git a/nifty5/operators/power_distributor.py b/nifty5/operators/power_distributor.py
index 3afe7c5a97925f1dfd684eb9646548de9a7f0551..05ab354d73e593f09e605106beb54ad602e8b38f 100644
--- a/nifty5/operators/power_distributor.py
+++ b/nifty5/operators/power_distributor.py
@@ -17,11 +17,12 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
-from .dof_distributor import DOFDistributor
 from ..domain_tuple import DomainTuple
-from ..utilities import infer_space
 from ..domains.power_space import PowerSpace
+from ..utilities import infer_space
+from .dof_distributor import DOFDistributor
 
 
 class PowerDistributor(DOFDistributor):
diff --git a/nifty5/operators/qht_operator.py b/nifty5/operators/qht_operator.py
index 31f7ce166ff6d1e6ed9af8d664ddf6cf2d4047e5..69e27349d6cac71ba9b74c316649824d52a9b108 100644
--- a/nifty5/operators/qht_operator.py
+++ b/nifty5/operators/qht_operator.py
@@ -17,10 +17,11 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
+from .. import dobj
 from ..compat import *
 from ..domain_tuple import DomainTuple
 from ..field import Field
-from .. import dobj
 from ..utilities import hartley
 from .linear_operator import LinearOperator
 
diff --git a/nifty5/operators/sampling_enabler.py b/nifty5/operators/sampling_enabler.py
index 512fc0548754a364f7a4fb245b310f2f3c86ac58..7bbe0b4f67c6dd8c0b5eec567b1228416f54ec53 100644
--- a/nifty5/operators/sampling_enabler.py
+++ b/nifty5/operators/sampling_enabler.py
@@ -17,8 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
+
+from ..compat import *
 from ..minimization.conjugate_gradient import ConjugateGradient
 from ..minimization.quadratic_energy import QuadraticEnergy
 from .endomorphic_operator import EndomorphicOperator
diff --git a/nifty5/operators/sandwich_operator.py b/nifty5/operators/sandwich_operator.py
index 577fd757e8221b1fb6d5a31dfe96193163509f25..3b8fd5bdee0edd643ec7ed16bf8295dc23c5b5f1 100644
--- a/nifty5/operators/sandwich_operator.py
+++ b/nifty5/operators/sandwich_operator.py
@@ -17,11 +17,13 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
-from .linear_operator import LinearOperator
+
+from ..compat import *
 from .diagonal_operator import DiagonalOperator
 from .endomorphic_operator import EndomorphicOperator
+from .linear_operator import LinearOperator
 from .scaling_operator import ScalingOperator
 
 
diff --git a/nifty5/operators/scaling_operator.py b/nifty5/operators/scaling_operator.py
index f2e659ed7ee637fe901d187657d4eb568f5da2c6..ad9037b9416fe1f9a9ce4558bc72c634e8915aaf 100644
--- a/nifty5/operators/scaling_operator.py
+++ b/nifty5/operators/scaling_operator.py
@@ -17,13 +17,15 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
+
+from ..compat import *
+from ..domain_tuple import DomainTuple
 from ..field import Field
 from ..multi.multi_field import MultiField
-from .endomorphic_operator import EndomorphicOperator
-from ..domain_tuple import DomainTuple
 from ..sugar import full
+from .endomorphic_operator import EndomorphicOperator
 
 
 class ScalingOperator(EndomorphicOperator):
diff --git a/nifty5/operators/selection_operator.py b/nifty5/operators/selection_operator.py
index 7a827618fc50d7fcc02ff6fba09716f4def25585..d7ebad584a3b21f46c45456e4385fbb57ab11465 100644
--- a/nifty5/operators/selection_operator.py
+++ b/nifty5/operators/selection_operator.py
@@ -17,9 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
-from .linear_operator import LinearOperator
 from ..multi.multi_domain import MultiDomain
+from .linear_operator import LinearOperator
 
 
 class SelectionOperator(LinearOperator):
diff --git a/nifty5/operators/sht_operator.py b/nifty5/operators/sht_operator.py
index d2ed53812f7c655cab96d4e0534843be7a802c1e..d6848e607f9012a055233e253ae19059c96c39b5 100644
--- a/nifty5/operators/sht_operator.py
+++ b/nifty5/operators/sht_operator.py
@@ -17,15 +17,16 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
+
+from .. import dobj, utilities
+from ..compat import *
 from ..domain_tuple import DomainTuple
-from .linear_operator import LinearOperator
-from .. import dobj
-from .. import utilities
-from ..field import Field
 from ..domains.gl_space import GLSpace
 from ..domains.lm_space import LMSpace
+from ..field import Field
+from .linear_operator import LinearOperator
 
 
 class SHTOperator(LinearOperator):
diff --git a/nifty5/operators/slope_operator.py b/nifty5/operators/slope_operator.py
index 3d0ef5faad424a06c26384c357649b43f713ba24..f4f5ce90c08c4bdd326875d4527b8627148697cc 100644
--- a/nifty5/operators/slope_operator.py
+++ b/nifty5/operators/slope_operator.py
@@ -17,8 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
+
 import numpy as np
+
+from ..compat import *
 from ..domain_tuple import DomainTuple
 from ..field import Field
 from .linear_operator import LinearOperator
diff --git a/nifty5/operators/smoothness_operator.py b/nifty5/operators/smoothness_operator.py
index 92c05f9debdc8fd2d44de96fdecb066901717697..d85af13b4ac14c1c10e69aaa2eb4ef04b30e1a49 100644
--- a/nifty5/operators/smoothness_operator.py
+++ b/nifty5/operators/smoothness_operator.py
@@ -17,9 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
-from .scaling_operator import ScalingOperator
 from .laplace_operator import LaplaceOperator
+from .scaling_operator import ScalingOperator
 
 
 def SmoothnessOperator(domain, strength=1., logarithmic=True, space=None):
diff --git a/nifty5/operators/sum_operator.py b/nifty5/operators/sum_operator.py
index c5946c4de3f7f41d1ca31917e6cb17a78ce363b4..d8cb5e28c153755b3eb25e976651d676c5055449 100644
--- a/nifty5/operators/sum_operator.py
+++ b/nifty5/operators/sum_operator.py
@@ -17,10 +17,12 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
+import numpy as np
+
 from ..compat import *
 from ..utilities import my_sum
 from .linear_operator import LinearOperator
-import numpy as np
 
 
 class SumOperator(LinearOperator):
diff --git a/nifty5/operators/symmetrizing_operator.py b/nifty5/operators/symmetrizing_operator.py
index cc31d96a7908445a360beb31f2c14c62cde8d0c1..d14cee3f46a53ff777dab31e3400b3328acc8c17 100644
--- a/nifty5/operators/symmetrizing_operator.py
+++ b/nifty5/operators/symmetrizing_operator.py
@@ -17,11 +17,12 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
+from .. import dobj
 from ..compat import *
 from ..domain_tuple import DomainTuple
 from ..field import Field
 from .endomorphic_operator import EndomorphicOperator
-from .. import dobj
 
 
 # MR FIXME: we should make sure that the domain is a harmonic RGSpace, correct?
diff --git a/nifty5/plotting/plot.py b/nifty5/plotting/plot.py
index 5d52440b0c70d3e0f1490eaa0c625bd897d0acb0..c90a4f53b952b6c31e2ee23f34f627654beb250d 100644
--- a/nifty5/plotting/plot.py
+++ b/nifty5/plotting/plot.py
@@ -17,11 +17,14 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from ..compat import *
-import numpy as np
-from ..import Field, RGSpace, HPSpace, GLSpace, PowerSpace, dobj
+
 import os
 
+import numpy as np
+
+from ..compat import *
+from ..importField import GLSpace, HPSpace, PowerSpace, RGSpace, dobj
+
 # relevant properties:
 # - x/y size
 # - x/y/z log
diff --git a/nifty5/probing/utils.py b/nifty5/probing/utils.py
index 14438d27a1f7752879b14268776c167ae0cca424..9a68dfe481d8a5d2d3081988d9ad57d67b3523c4 100644
--- a/nifty5/probing/utils.py
+++ b/nifty5/probing/utils.py
@@ -17,6 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
 from ..field import Field
 
diff --git a/nifty5/sugar.py b/nifty5/sugar.py
index 0fd5d610162907f77cd281eb05ad7e1f3902a567..ea0c6b7d28a01f7c653a0b47e4681c04bf784d2e 100644
--- a/nifty5/sugar.py
+++ b/nifty5/sugar.py
@@ -17,19 +17,22 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from .compat import *
+
 import sys
+
 import numpy as np
+
+from . import dobj, utilities
+from .compat import *
+from .domain_tuple import DomainTuple
 from .domains.power_space import PowerSpace
 from .field import Field
-from .multi.multi_field import MultiField
+from .logger import logger
 from .multi.block_diagonal_operator import BlockDiagonalOperator
 from .multi.multi_domain import MultiDomain
+from .multi.multi_field import MultiField
 from .operators.diagonal_operator import DiagonalOperator
 from .operators.power_distributor import PowerDistributor
-from .domain_tuple import DomainTuple
-from . import dobj, utilities
-from .logger import logger
 
 __all__ = ['PS_field', 'power_analyze', 'create_power_operator',
            'create_harmonic_smoothing_operator', 'from_random',
diff --git a/nifty5/utilities.py b/nifty5/utilities.py
index afb8e23b43d1aad0576bf29dc72e37497c036623..de4b6e73ffa26684126222957eb7c91a860cfe21 100644
--- a/nifty5/utilities.py
+++ b/nifty5/utilities.py
@@ -17,12 +17,15 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
-from .compat import *
-import numpy as np
-from itertools import product
+
 import abc
-from future.utils import with_metaclass
 import collections
+from itertools import product
+
+import numpy as np
+from future.utils import with_metaclass
+
+from .compat import *
 
 __all__ = ["get_slice_list", "safe_cast", "parse_spaces", "infer_space",
            "memo", "NiftyMetaBase", "fft_prep", "hartley", "my_fftn_r2c",
diff --git a/setup.py b/setup.py
index bc18c7557ddc6054f4955c8d2b25c5e786db696b..928e2748b444bbee9e110d9069afe31bb5146ead 100644
--- a/setup.py
+++ b/setup.py
@@ -16,7 +16,7 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
-from setuptools import setup, find_packages
+from setuptools import find_packages, setup
 
 
 def write_version():
diff --git a/test/common.py b/test/common.py
index 5987f73e5280982ce9051b3ff8c230220ec35a3a..d6713742da5174e19dcf348d55c8240419f52864 100644
--- a/test/common.py
+++ b/test/common.py
@@ -17,8 +17,9 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from builtins import str
-from parameterized import parameterized
+
 import numpy as np
+from parameterized import parameterized
 
 np.seterr(all='raise', under='ignore')
 
diff --git a/test/test_energies/test_map.py b/test/test_energies/test_map.py
index f6709d3b3f86979d94db928ce28d7a5983274734..1cfb49867499d46d4c9ac40b8aefbfb30f31a433 100644
--- a/test/test_energies/test_map.py
+++ b/test/test_energies/test_map.py
@@ -17,11 +17,12 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 import unittest
-import nifty5 as ift
-import numpy as np
 from itertools import product
 from test.common import expand
 
+import nifty5 as ift
+import numpy as np
+
 
 def _flat_PS(k):
     return np.ones_like(k)
diff --git a/test/test_field.py b/test/test_field.py
index 42a5734201ed8843f9ac9c2046506584bc81152a..0d6b80679aa9c98ee6bda12ba72fdd02a9fb334a 100644
--- a/test/test_field.py
+++ b/test/test_field.py
@@ -17,12 +17,12 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 import unittest
-import numpy as np
-from numpy.testing import assert_equal, assert_allclose, assert_raises
 from itertools import product
-import nifty5 as ift
 from test.common import expand
 
+import nifty5 as ift
+import numpy as np
+from numpy.testing import assert_allclose, assert_equal, assert_raises
 
 SPACES = [ift.RGSpace((4,)), ift.RGSpace((5))]
 SPACE_COMBINATIONS = [(), SPACES[0], SPACES[1], SPACES]
diff --git a/test/test_minimization/test_minimizers.py b/test/test_minimization/test_minimizers.py
index 8607a8b982fed209fc6dc1dfe7d4e9f47ce3c507..e0b3601d1aa46546843f9773fae4863beff215c4 100644
--- a/test/test_minimization/test_minimizers.py
+++ b/test/test_minimization/test_minimizers.py
@@ -17,12 +17,13 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 import unittest
-import numpy as np
-from numpy.testing import assert_allclose, assert_equal
-import nifty5 as ift
 from itertools import product
 from test.common import expand
+
+import nifty5 as ift
+import numpy as np
 from nose.plugins.skip import SkipTest
+from numpy.testing import assert_allclose, assert_equal
 
 IC = ift.GradientNormController(tol_abs_gradnorm=1e-5, iteration_limit=1000)
 
diff --git a/test/test_multi_field.py b/test/test_multi_field.py
index 820d82da7a27080233414ee0030c8de6ceb9fc3b..bddf7ee5d6b19572167272af9a5fc22b022d0d35 100644
--- a/test/test_multi_field.py
+++ b/test/test_multi_field.py
@@ -17,11 +17,10 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 import unittest
-import numpy as np
-from numpy.testing import assert_equal, assert_allclose, assert_raises
-from itertools import product
+
 import nifty5 as ift
-from test.common import expand
+import numpy as np
+from numpy.testing import assert_allclose, assert_equal
 
 dom = ift.makeDomain({"d1": ift.RGSpace(10)})
 
diff --git a/test/test_operators/test_adjoint.py b/test/test_operators/test_adjoint.py
index 9df172961406ce7b825b375ab020083a679d5132..6c93c69fa7cfa577ef809c379a16779861535a3d 100644
--- a/test/test_operators/test_adjoint.py
+++ b/test/test_operators/test_adjoint.py
@@ -17,11 +17,11 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 import unittest
-import nifty5 as ift
-import numpy as np
 from itertools import product
 from test.common import expand
 
+import nifty5 as ift
+import numpy as np
 
 _h_RG_spaces = [ift.RGSpace(7, distances=0.2, harmonic=True),
                 ift.RGSpace((12, 46), distances=(.2, .3), harmonic=True)]
diff --git a/test/test_operators/test_composed_operator.py b/test/test_operators/test_composed_operator.py
index 1558a89b217c09c2161de6638b8e0ec3c090a285..faf4251b45b98bbf1d8a5f29cb954fc8c89c571f 100644
--- a/test/test_operators/test_composed_operator.py
+++ b/test/test_operators/test_composed_operator.py
@@ -17,11 +17,12 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 import unittest
-from numpy.testing import assert_allclose, assert_equal
-import nifty5 as ift
 from itertools import product
 from test.common import expand
 
+import nifty5 as ift
+from numpy.testing import assert_allclose, assert_equal
+
 
 class ComposedOperator_Tests(unittest.TestCase):
     spaces = [ift.RGSpace(4),
diff --git a/test/test_operators/test_diagonal_operator.py b/test/test_operators/test_diagonal_operator.py
index d8ade104c0cab187167e77e205f7734337ab9dbe..2c30a56e121471a874c50084aaf1125950b5da2e 100644
--- a/test/test_operators/test_diagonal_operator.py
+++ b/test/test_operators/test_diagonal_operator.py
@@ -17,12 +17,14 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import division
+
 import unittest
-from numpy.testing import assert_equal, assert_allclose
-import nifty5 as ift
 from itertools import product
 from test.common import expand
 
+import nifty5 as ift
+from numpy.testing import assert_allclose, assert_equal
+
 
 class DiagonalOperator_Tests(unittest.TestCase):
     spaces = [ift.RGSpace(4),
diff --git a/test/test_operators/test_fft_operator.py b/test/test_operators/test_fft_operator.py
index 3c84ffa5ef85b2d2f39b4b9c6104be9ebf6f13e5..24ec9fe1f74246ed8710388c45d06bf8ed4ec322 100644
--- a/test/test_operators/test_fft_operator.py
+++ b/test/test_operators/test_fft_operator.py
@@ -17,13 +17,15 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import division
+
 import unittest
-import numpy as np
-from numpy.testing import assert_allclose
-import nifty5 as ift
 from itertools import product
 from test.common import expand
 
+import nifty5 as ift
+import numpy as np
+from numpy.testing import assert_allclose
+
 
 def _get_rtol(tp):
     if (tp == np.float64) or (tp == np.complex128):
diff --git a/test/test_operators/test_harmonic_transform_operator.py b/test/test_operators/test_harmonic_transform_operator.py
index 0bd7a6c738de2ea3ab4c524f02f016763867a740..cad14eb7d077322bfe31f447e0ab069b261b425a 100644
--- a/test/test_operators/test_harmonic_transform_operator.py
+++ b/test/test_operators/test_harmonic_transform_operator.py
@@ -17,13 +17,15 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import division
+
 import unittest
-import numpy as np
-from numpy.testing import assert_allclose
-import nifty5 as ift
 from itertools import product
 from test.common import expand
 
+import nifty5 as ift
+import numpy as np
+from numpy.testing import assert_allclose
+
 
 def _get_rtol(tp):
     if (tp == np.float64) or (tp == np.complex128):
diff --git a/test/test_operators/test_laplace_operator.py b/test/test_operators/test_laplace_operator.py
index e5cd5a0f06474df23af1fee5fcce64bf30e1f374..6891745a527e4666c1a064bdeec86f0b6db56fd0 100644
--- a/test/test_operators/test_laplace_operator.py
+++ b/test/test_operators/test_laplace_operator.py
@@ -17,12 +17,13 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 import unittest
-import numpy as np
-import nifty5 as ift
-from numpy.testing import assert_allclose
 from itertools import product
 from test.common import expand
 
+import nifty5 as ift
+import numpy as np
+from numpy.testing import assert_allclose
+
 
 class LaplaceOperatorTests(unittest.TestCase):
     @expand(product([None, False, True], [False, True], [10, 100, 1000]))
diff --git a/test/test_operators/test_smoothing_operator.py b/test/test_operators/test_smoothing_operator.py
index c040d8464f27f3f8cc423bc09f04bb3e9685237d..a07c30088d73114c4922fff0b5f7bed318296183 100644
--- a/test/test_operators/test_smoothing_operator.py
+++ b/test/test_operators/test_smoothing_operator.py
@@ -17,12 +17,13 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 import unittest
-import numpy as np
-from numpy.testing import assert_allclose
-import nifty5 as ift
 from itertools import product
 from test.common import expand
 
+import nifty5 as ift
+import numpy as np
+from numpy.testing import assert_allclose
+
 
 def _get_rtol(tp):
     if (tp == np.float64) or (tp == np.complex128):
diff --git a/test/test_spaces/test_gl_space.py b/test/test_spaces/test_gl_space.py
index 89160b123a7c93a4cbd3003ef2b4780a84377fd3..a66f09fbcdd62ecc8652eea5cf7d02f9d231e0f1 100644
--- a/test/test_spaces/test_gl_space.py
+++ b/test/test_spaces/test_gl_space.py
@@ -16,13 +16,14 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
+import itertools
 import unittest
+from test.common import expand
+
 import numpy as np
-import itertools
-from numpy.testing import assert_, assert_equal, assert_raises,\
-        assert_almost_equal
 from nifty5 import GLSpace
-from test.common import expand
+from numpy.testing import (assert_, assert_almost_equal, assert_equal,
+                           assert_raises)
 
 # [nlat, nlon, expected]
 CONSTRUCTOR_CONFIGS = [
diff --git a/test/test_spaces/test_hp_space.py b/test/test_spaces/test_hp_space.py
index 17c5b6b3d0d93254bcbd0204f3473827cb713db0..3104c678cffd471d629584227ddf43c39b7a047f 100644
--- a/test/test_spaces/test_hp_space.py
+++ b/test/test_spaces/test_hp_space.py
@@ -17,12 +17,14 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import division
+
 import unittest
+from test.common import expand
+
 import numpy as np
-from numpy.testing import assert_, assert_equal, assert_raises,\
-                          assert_almost_equal
 from nifty5 import HPSpace
-from test.common import expand
+from numpy.testing import (assert_, assert_almost_equal, assert_equal,
+                           assert_raises)
 
 # [nside, expected]
 CONSTRUCTOR_CONFIGS = [
diff --git a/test/test_spaces/test_interface.py b/test/test_spaces/test_interface.py
index 77663f082855dae063ee9ff76e9b1e3cf6796c4f..f2871372d276efffa75740e8f4aa5473a7ee9bd8 100644
--- a/test/test_spaces/test_interface.py
+++ b/test/test_spaces/test_interface.py
@@ -17,11 +17,12 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 import unittest
-from numpy.testing import assert_
 from itertools import product
-from types import LambdaType
 from test.common import expand
+from types import LambdaType
+
 import nifty5 as ift
+from numpy.testing import assert_
 
 spaces = [ift.RGSpace(4),
           ift.PowerSpace(ift.RGSpace((4, 4), harmonic=True)),
diff --git a/test/test_spaces/test_lm_space.py b/test/test_spaces/test_lm_space.py
index c4232705a5b2b2da45918607ad4cc5a055399094..e17d3f73630ce46fbfcd16edd09a95a76400d225 100644
--- a/test/test_spaces/test_lm_space.py
+++ b/test/test_spaces/test_lm_space.py
@@ -17,13 +17,14 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import division
+
 import unittest
-import numpy as np
-from numpy.testing import assert_, assert_equal, assert_raises,\
-        assert_allclose
-import nifty5 as ift
 from test.common import expand
 
+import nifty5 as ift
+import numpy as np
+from numpy.testing import assert_, assert_allclose, assert_equal, assert_raises
+
 # [lmax, expected]
 CONSTRUCTOR_CONFIGS = [
         [5, None, {
diff --git a/test/test_spaces/test_power_space.py b/test/test_spaces/test_power_space.py
index a29a19c2d8f6375a68f597ee52bf7a8088b9c92f..069233af5499f262694a1f2553a229d724328192 100644
--- a/test/test_spaces/test_power_space.py
+++ b/test/test_spaces/test_power_space.py
@@ -17,13 +17,14 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import division
+
 import unittest
-import numpy as np
-from numpy.testing import assert_, assert_equal, assert_allclose,\
-        assert_raises
-import nifty5 as ift
+from itertools import chain, product
 from test.common import expand
-from itertools import product, chain
+
+import nifty5 as ift
+import numpy as np
+from numpy.testing import assert_, assert_allclose, assert_equal, assert_raises
 
 HARMONIC_SPACES = [ift.RGSpace((8,), harmonic=True),
                    ift.RGSpace((7, 8), harmonic=True),
diff --git a/test/test_spaces/test_rg_space.py b/test/test_spaces/test_rg_space.py
index ae757605fa022ef2f1dca79bb1e5ef10111aeded..d2152252cbd60fa0d028ce9c1f3778a95644428a 100644
--- a/test/test_spaces/test_rg_space.py
+++ b/test/test_spaces/test_rg_space.py
@@ -17,12 +17,14 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import division
+
 import unittest
-import numpy as np
-from numpy.testing import assert_, assert_equal, assert_allclose
-import nifty5 as ift
 from test.common import expand
 
+import nifty5 as ift
+import numpy as np
+from numpy.testing import assert_, assert_allclose, assert_equal
+
 # [shape, distances, harmonic, expected]
 CONSTRUCTOR_CONFIGS = [
         [(8,), None, False,