diff --git a/nifty5/minimization/energy.py b/nifty5/minimization/energy.py
index 07df8fb6c5a876a2f09c1e680ca0b9be0f725b5d..f567a0e38cee4f29dc51f2141d2bf2de7b5ce268 100644
--- a/nifty5/minimization/energy.py
+++ b/nifty5/minimization/energy.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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/gradient_norm_controller.py b/nifty5/minimization/gradient_norm_controller.py
index 457eb9d95eb1ee1fa442582193ff29c3497a015b..b17dba54beb43eb2168588a882e2ef79a60fa237 100644
--- a/nifty5/minimization/gradient_norm_controller.py
+++ b/nifty5/minimization/gradient_norm_controller.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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
 
diff --git a/nifty5/minimization/line_energy.py b/nifty5/minimization/line_energy.py
index 477ad01df6bbc5bbddfc841569420929774a6717..bb7ccb0d13a42d4876346578cb696899f9e786e4 100644
--- a/nifty5/minimization/line_energy.py
+++ b/nifty5/minimization/line_energy.py
@@ -16,6 +16,9 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
+from __future__ import absolute_import, division, print_function
+from ..compat import *
+
 
 class LineEnergy(object):
     """ Evaluates an underlying Energy along a certain line direction.
diff --git a/nifty5/minimization/line_search.py b/nifty5/minimization/line_search.py
index 49871dc0974ca09eff0db7e3358568c8272257ed..0e77f26a6fad147fc68a18a56c795f7b41625b7a 100644
--- a/nifty5/minimization/line_search.py
+++ b/nifty5/minimization/line_search.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
+from __future__ import absolute_import, division, print_function
+from ..compat import *
 import abc
 from ..utilities import NiftyMetaBase
 
diff --git a/nifty5/minimization/minimizer.py b/nifty5/minimization/minimizer.py
index e98412c871ba1750108d06f2e2672534d593b355..89058659ec125bffe409c27621452a1ee58eabc2 100644
--- a/nifty5/minimization/minimizer.py
+++ b/nifty5/minimization/minimizer.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
+from __future__ import absolute_import, division, print_function
+from ..compat import *
 import abc
 from ..utilities import NiftyMetaBase
 
diff --git a/nifty5/minimization/quadratic_energy.py b/nifty5/minimization/quadratic_energy.py
index 2467d6c5d554ddf1cf027c2d19c6cb1ec31160f1..9e27257e6df82e6e16cf37a66622b38763ef5935 100644
--- a/nifty5/minimization/quadratic_energy.py
+++ b/nifty5/minimization/quadratic_energy.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 bdcdf32d6dc42a5aa0f00af6a366319907630924..c8dd59d611ec01f27d6f51c540a5efde9cff592b 100644
--- a/nifty5/minimization/relaxed_newton.py
+++ b/nifty5/minimization/relaxed_newton.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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/models/binary_helpers.py b/nifty5/models/binary_helpers.py
index da87c5e049361239439d9f0f05293e41ce97c6e5..a778f152f65ec0af13477f5edc1f8571c062dfa3 100644
--- a/nifty5/models/binary_helpers.py
+++ b/nifty5/models/binary_helpers.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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
 from .model import Model
diff --git a/nifty5/models/constant.py b/nifty5/models/constant.py
index e652758962d9db24350b726905874e00044bd5bf..3a044d8809e5bfa79d2e6bf1e06e3475d44a42f7 100644
--- a/nifty5/models/constant.py
+++ b/nifty5/models/constant.py
@@ -15,6 +15,9 @@
 #
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 9612400db2abd2ebfb9dc406ba981152d0947e63..b0ff0f3c05d738bb1412893c95c00e0ba1cb5b3a 100644
--- a/nifty5/models/linear_model.py
+++ b/nifty5/models/linear_model.py
@@ -15,6 +15,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 1ad11593bf8c8e658c5da40d27a0b6e13de36367..02605dfa1f187e727f50d32281ea1d88cda9ca52 100644
--- a/nifty5/models/local_nonlinearity.py
+++ b/nifty5/models/local_nonlinearity.py
@@ -16,9 +16,10 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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
-
 from .model import Model
 
 
diff --git a/nifty5/models/model.py b/nifty5/models/model.py
index 259a22c6f54845c45e8a6c881c9cc862972555dd..5ab8623100fba6ddad0125695902938746c1cb2f 100644
--- a/nifty5/models/model.py
+++ b/nifty5/models/model.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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
 from ..operators.selection_operator import SelectionOperator
diff --git a/nifty5/models/multi_model.py b/nifty5/models/multi_model.py
index 0a1d7ca84d9b697baf4e57d2ff890c62fcd3e314..2033923daf852ac0ddc4342b8b219843674835fa 100644
--- a/nifty5/models/multi_model.py
+++ b/nifty5/models/multi_model.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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
 from ..operators.multi_adaptor import MultiAdaptor
diff --git a/nifty5/models/variable.py b/nifty5/models/variable.py
index c5ad6892eb15539327a830049f852e84e02e3dbb..3937f6dff996d9f4806f7e1f92bcb03602b9c430 100644
--- a/nifty5/models/variable.py
+++ b/nifty5/models/variable.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 d448f46d3a2370ee3cc97b240efc0767ba7539b9..ad62bd9b490600ef4305f8b640c4bba789a3762c 100644
--- a/nifty5/multi/block_diagonal_operator.py
+++ b/nifty5/multi/block_diagonal_operator.py
@@ -1,3 +1,5 @@
+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
diff --git a/nifty5/multi/multi_field.py b/nifty5/multi/multi_field.py
index bb6004c5f4e9ae56a15a4b38e05140e75ade83ee..1b7478879db2a00a21a227272433ec8a96502678 100644
--- a/nifty5/multi/multi_field.py
+++ b/nifty5/multi/multi_field.py
@@ -16,21 +16,14 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
+from __future__ import absolute_import, division, print_function
+from ..compat import *
 from ..field import Field
 import numpy as np
 from .multi_domain import MultiDomain
 from ..utilities import frozendict
 
 
-# ways of creating MultiFields:
-# - (Field)
-# - (Field, name)
-# - (dict {string, Field})
-# - MultiDomain, dict(string, Field)
-
-# new methods
-# .field(name)
-# .domain(name)
 class MultiField(object):
     def __init__(self, domain, val):
         """
diff --git a/nifty5/operators/chain_operator.py b/nifty5/operators/chain_operator.py
index 4d6cc7ee29797b0def39cfd8c359f71de55335d6..40f6d844c93b7f22800373262433a6d6bfafa632 100644
--- a/nifty5/operators/chain_operator.py
+++ b/nifty5/operators/chain_operator.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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
 
diff --git a/nifty5/operators/dof_distributor.py b/nifty5/operators/dof_distributor.py
index 305afbd2a8b3bd84844df7254d9eb8c8ba78e875..efcace429cc3e6863f1141290cf0c83c25d8142c 100644
--- a/nifty5/operators/dof_distributor.py
+++ b/nifty5/operators/dof_distributor.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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
diff --git a/nifty5/operators/domain_distributor.py b/nifty5/operators/domain_distributor.py
index aa5b39474e4bab73307077ce561b2e244b23fcc2..c804f2e0fed26e39677b0e2256de9f35e2c2ce3e 100644
--- a/nifty5/operators/domain_distributor.py
+++ b/nifty5/operators/domain_distributor.py
@@ -1,6 +1,7 @@
+from __future__ import absolute_import, division, print_function
+from ..compat import *
 import numpy as np
 from ..field import Field
-
 from .. import dobj
 from ..domain_tuple import DomainTuple
 from .linear_operator import LinearOperator
diff --git a/nifty5/operators/endomorphic_operator.py b/nifty5/operators/endomorphic_operator.py
index af511f9acdb08d157a15ed82bad822ffb82b84ea..39edb7b2907fa273fb88f7b7d35c00ad9a6a7de1 100644
--- a/nifty5/operators/endomorphic_operator.py
+++ b/nifty5/operators/endomorphic_operator.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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
 import numpy as np
 
diff --git a/nifty5/operators/exp_transform.py b/nifty5/operators/exp_transform.py
index 88b0bc7d6083b851644f1fb07943bedca45139f8..900c287d4765ab1b5da72c07ba17ee5134506f41 100644
--- a/nifty5/operators/exp_transform.py
+++ b/nifty5/operators/exp_transform.py
@@ -1,5 +1,6 @@
+from __future__ import absolute_import, division, print_function
+from ..compat import *
 import numpy as np
-
 from ..domain_tuple import DomainTuple
 from ..domains.power_space import PowerSpace
 from ..domains.rg_space import RGSpace
diff --git a/nifty5/operators/fft_operator.py b/nifty5/operators/fft_operator.py
index 41a2c802fa824ab3e49cbdb9dbc4327abde179a8..5fa35e40a40a6624c0ad0dca04464340c463c478 100644
--- a/nifty5/operators/fft_operator.py
+++ b/nifty5/operators/fft_operator.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 ..domain_tuple import DomainTuple
 from ..domains.rg_space import RGSpace
diff --git a/nifty5/operators/fft_smoothing_operator.py b/nifty5/operators/fft_smoothing_operator.py
index cdc211bbbcca187af35707c3016859d605ab058d..08fce06bea00b94aeffe436e1e61f7afe6294e13 100644
--- a/nifty5/operators/fft_smoothing_operator.py
+++ b/nifty5/operators/fft_smoothing_operator.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 ..utilities import infer_space
diff --git a/nifty5/operators/geometry_remover.py b/nifty5/operators/geometry_remover.py
index 759beed575ff82b6cf0c2daa3c36d8a367a86a44..67567ddb1c1616355e4886adf466fde91d31481c 100644
--- a/nifty5/operators/geometry_remover.py
+++ b/nifty5/operators/geometry_remover.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 .linear_operator import LinearOperator
diff --git a/nifty5/operators/harmonic_transform_operator.py b/nifty5/operators/harmonic_transform_operator.py
index 4be0f748b57aa686e64bb5dd012b49b04b1dbb95..8c984f0f11e7f41f04e06cfbeb258fd85cb0fee4 100644
--- a/nifty5/operators/harmonic_transform_operator.py
+++ b/nifty5/operators/harmonic_transform_operator.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 ..domains.rg_space import RGSpace
 from .linear_operator import LinearOperator
diff --git a/nifty5/operators/inversion_enabler.py b/nifty5/operators/inversion_enabler.py
index 5efd5848b57248acaaa9ac705db856713c885d19..f612eeeb07f9e8b8fac2717fcee0289ea2549282 100644
--- a/nifty5/operators/inversion_enabler.py
+++ b/nifty5/operators/inversion_enabler.py
@@ -16,8 +16,9 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 ..logger import logger
 from ..minimization.conjugate_gradient import ConjugateGradient
 from ..minimization.iteration_controller import IterationController
diff --git a/nifty5/operators/laplace_operator.py b/nifty5/operators/laplace_operator.py
index 450e9d1c436a89799039fc2a029df9cb7a34ec79..6ed7aa7c91cd4b190759ccbe01ba03cc3c911880 100644
--- a/nifty5/operators/laplace_operator.py
+++ b/nifty5/operators/laplace_operator.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 ..domains.power_space import PowerSpace
diff --git a/nifty5/operators/linear_operator.py b/nifty5/operators/linear_operator.py
index 00660f173b26d97cb94d61b9f33f351f7ae9149f..34f4d3d099ae41c4b7a73ce6fb59a93d2d2080d9 100644
--- a/nifty5/operators/linear_operator.py
+++ b/nifty5/operators/linear_operator.py
@@ -16,9 +16,10 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 ..utilities import NiftyMetaBase
 
 
diff --git a/nifty5/operators/mask_operator.py b/nifty5/operators/mask_operator.py
index 87407ee9a4bf4a44ab517c04a15ceca867aacc77..a9b39e8ce9bb6790e230f07d95a87755df50616f 100644
--- a/nifty5/operators/mask_operator.py
+++ b/nifty5/operators/mask_operator.py
@@ -16,8 +16,9 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 ..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 4272c19f41c472ec767ea3d83ad1dc2d6edc1fe3..50cbfbc2ea566c7951de5804363ee80bf73fbbd8 100644
--- a/nifty5/operators/multi_adaptor.py
+++ b/nifty5/operators/multi_adaptor.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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
 
 
diff --git a/nifty5/operators/operator_adapter.py b/nifty5/operators/operator_adapter.py
index dcf2003db8fda9f5a2745bad52cd78519f023128..678ce58afc36793e16ec2bb4202a985028b1b971 100644
--- a/nifty5/operators/operator_adapter.py
+++ b/nifty5/operators/operator_adapter.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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
 import numpy as np
 
diff --git a/nifty5/operators/power_distributor.py b/nifty5/operators/power_distributor.py
index a141ac741a755d6ad66358739a556ca10d1931b2..3afe7c5a97925f1dfd684eb9646548de9a7f0551 100644
--- a/nifty5/operators/power_distributor.py
+++ b/nifty5/operators/power_distributor.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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
diff --git a/nifty5/operators/qht_operator.py b/nifty5/operators/qht_operator.py
index 8da26cbfe6de65505c11cb9ecb338af23e9558bf..b782116e06f8aaba19bd229b6f6e7247a85027a2 100644
--- a/nifty5/operators/qht_operator.py
+++ b/nifty5/operators/qht_operator.py
@@ -1,3 +1,5 @@
+from __future__ import absolute_import, division, print_function
+from ..compat import *
 from ..domain_tuple import DomainTuple
 from ..field import Field
 from .. import dobj
diff --git a/nifty5/operators/sampling_enabler.py b/nifty5/operators/sampling_enabler.py
index 004b894ae546bcf958a55ee8af133b982350d581..512fc0548754a364f7a4fb245b310f2f3c86ac58 100644
--- a/nifty5/operators/sampling_enabler.py
+++ b/nifty5/operators/sampling_enabler.py
@@ -16,8 +16,9 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 ..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 5cf8764a95919b3c5e97c01fa365c0e328564bdc..577fd757e8221b1fb6d5a31dfe96193163509f25 100644
--- a/nifty5/operators/sandwich_operator.py
+++ b/nifty5/operators/sandwich_operator.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 .diagonal_operator import DiagonalOperator
diff --git a/nifty5/operators/selection_operator.py b/nifty5/operators/selection_operator.py
index 71fc3e8606f829988b2da7605a12032dc5cc2040..7a827618fc50d7fcc02ff6fba09716f4def25585 100644
--- a/nifty5/operators/selection_operator.py
+++ b/nifty5/operators/selection_operator.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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
 
diff --git a/nifty5/operators/sht_operator.py b/nifty5/operators/sht_operator.py
index c2b2568ef1930e6cf4193403b14c72a11f29e22e..d2ed53812f7c655cab96d4e0534843be7a802c1e 100644
--- a/nifty5/operators/sht_operator.py
+++ b/nifty5/operators/sht_operator.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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 ..domain_tuple import DomainTuple
 from .linear_operator import LinearOperator
diff --git a/nifty5/operators/slope_operator.py b/nifty5/operators/slope_operator.py
index bb07e0a70c2404a0881b0ab6b3bcd4a4f2a70224..71ca7b254a614f17dd5186ff0cc03b1cb9dcd802 100644
--- a/nifty5/operators/slope_operator.py
+++ b/nifty5/operators/slope_operator.py
@@ -1,5 +1,6 @@
+from __future__ import absolute_import, division, print_function
+from ..compat import *
 import numpy as np
-
 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 ba6aa76a3a18e4abe3b764c7f033e3171b03ee22..92c05f9debdc8fd2d44de96fdecb066901717697 100644
--- a/nifty5/operators/smoothness_operator.py
+++ b/nifty5/operators/smoothness_operator.py
@@ -16,6 +16,8 @@
 # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
 # 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
 
diff --git a/nifty5/operators/symmetrizing_operator.py b/nifty5/operators/symmetrizing_operator.py
index 44d2aba7fbdbc4103e81bf5797c5430f88c04f30..6f0f15820da6ea5feb2237dec0aa6e389c69b0ad 100644
--- a/nifty5/operators/symmetrizing_operator.py
+++ b/nifty5/operators/symmetrizing_operator.py
@@ -1,3 +1,5 @@
+from __future__ import absolute_import, division, print_function
+from ..compat import *
 from ..domain_tuple import DomainTuple
 from ..field import Field
 from .endomorphic_operator import EndomorphicOperator