diff --git a/nifty5/library/amplitude_model.py b/nifty5/library/amplitude_model.py
index 9d3018a29d9e116438d2bc4143f55f9ac5bbe47b..5f599503a22187c4cbed09efd8f3a07aced06427 100644
--- a/nifty5/library/amplitude_model.py
+++ b/nifty5/library/amplitude_model.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 ..domains.power_space import PowerSpace
 from ..domains.unstructured_domain import UnstructuredDomain
 from ..field import Field
diff --git a/nifty5/library/apply_data.py b/nifty5/library/apply_data.py
index 4df78fdce05a7f2b18dca5dbff937e095135c003..7a90cfde2b98f09ca982c07c5a0a5a130b6fa35d 100644
--- a/nifty5/library/apply_data.py
+++ b/nifty5/library/apply_data.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/library/bernoulli_energy.py b/nifty5/library/bernoulli_energy.py
index c056b3a7a76818509368c898ea51321f9265801e..4ac0c48336b4f0a2200e1b52c6a972a201c3010c 100644
--- a/nifty5/library/bernoulli_energy.py
+++ b/nifty5/library/bernoulli_energy.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 numpy import inf, isnan
+
+from ..compat import *
 from ..minimization.energy import Energy
 from ..operators.sandwich_operator import SandwichOperator
 from ..sugar import log, makeOp
diff --git a/nifty5/library/correlated_fields.py b/nifty5/library/correlated_fields.py
index 2b4f0a5570ac8bc46ab78efce3cd0ee4ed4038bb..c30b2072a38423b6bb21bf822f2fa0c7c189390e 100644
--- a/nifty5/library/correlated_fields.py
+++ b/nifty5/library/correlated_fields.py
@@ -17,17 +17,17 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
-from ..operators.fft_operator import FFTOperator
+from ..domain_tuple import DomainTuple
 from ..field import Field
-from ..multi.multi_field import MultiField
 from ..models.local_nonlinearity import PointwiseExponential
-from ..operators.power_distributor import PowerDistributor
 from ..models.variable import Variable
-from ..domain_tuple import DomainTuple
+from ..multi.multi_field import MultiField
 from ..operators.domain_distributor import DomainDistributor
-from ..operators.harmonic_transform_operator \
-    import HarmonicTransformOperator
+from ..operators.fft_operator import FFTOperator
+from ..operators.harmonic_transform_operator import HarmonicTransformOperator
+from ..operators.power_distributor import PowerDistributor
 
 
 def make_correlated_field(s_space, amplitude_model):
diff --git a/nifty5/library/gaussian_energy.py b/nifty5/library/gaussian_energy.py
index 5f726fcccdba2de5b734f2d86edf8c601d02951b..9ed61b50a8946d4964261832a00f6f72db555980 100644
--- a/nifty5/library/gaussian_energy.py
+++ b/nifty5/library/gaussian_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 ..minimization.energy import Energy
 from ..operators.sandwich_operator import SandwichOperator
diff --git a/nifty5/library/los_response.py b/nifty5/library/los_response.py
index 45be9b47e710f548315cb4ac7b87c14071cbbdc6..3176361fea1cf25c71617bdcb47dd780cf4c3cf0 100644
--- a/nifty5/library/los_response.py
+++ b/nifty5/library/los_response.py
@@ -17,17 +17,19 @@
 # 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 scipy.special import erfc
 from scipy.sparse import coo_matrix
 from scipy.sparse.linalg import aslinearoperator
-from ..operators.linear_operator import LinearOperator
+from scipy.special import erfc
+
+from .. import dobj
+from ..compat import *
 from ..domain_tuple import DomainTuple
 from ..domains.rg_space import RGSpace
 from ..domains.unstructured_domain import UnstructuredDomain
 from ..field import Field
-from .. import dobj
+from ..operators.linear_operator import LinearOperator
 
 
 def _gaussian_error_function(x):
diff --git a/nifty5/library/point_sources.py b/nifty5/library/point_sources.py
index 0fb7cb9719a7cd1a14e408f7a01ce2dce75eedec..7ae8250ad737bb7eaa58e9c57176c9760c3ef3d8 100644
--- a/nifty5/library/point_sources.py
+++ b/nifty5/library/point_sources.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 scipy.stats import invgamma, norm
+
+from ..compat import *
 from ..field import Field
-from ..sugar import makeOp
-from ..multi.multi_field import MultiField
 from ..models.model import Model
-
+from ..multi.multi_field import MultiField
 from ..operators.selection_operator import SelectionOperator
+from ..sugar import makeOp
 from ..utilities import memo
 
 
diff --git a/nifty5/library/poissonian_energy.py b/nifty5/library/poissonian_energy.py
index 4f910876335fa2aca2e10c739e0addcdce50bfc2..e6eadc45ea71de83ad19ca9e0accffef1bd20aa2 100644
--- a/nifty5/library/poissonian_energy.py
+++ b/nifty5/library/poissonian_energy.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 numpy import inf, isnan
+
+from ..compat import *
 from ..minimization.energy import Energy
 from ..operators.sandwich_operator import SandwichOperator
 from ..sugar import log, makeOp
diff --git a/nifty5/library/wiener_filter_curvature.py b/nifty5/library/wiener_filter_curvature.py
index ea8d8244fa051c141dbee071680ef1e578cedf6b..d878e4de7669607d8b129d5b9fcc92b19d5f8867 100644
--- a/nifty5/library/wiener_filter_curvature.py
+++ b/nifty5/library/wiener_filter_curvature.py
@@ -17,10 +17,11 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 from __future__ import absolute_import, division, print_function
+
 from ..compat import *
-from ..operators.sandwich_operator import SandwichOperator
 from ..operators.inversion_enabler import InversionEnabler
 from ..operators.sampling_enabler import SamplingEnabler
+from ..operators.sandwich_operator import SandwichOperator
 
 
 def WienerFilterCurvature(R, N, S, iteration_controller=None,
diff --git a/nifty5/library/wiener_filter_energy.py b/nifty5/library/wiener_filter_energy.py
index 62f57cfb2884661e84a9cc36278ac1f45a7deb32..dc46ab090bc967342840a492df354183bf8964ae 100644
--- a/nifty5/library/wiener_filter_energy.py
+++ b/nifty5/library/wiener_filter_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 ..minimization.quadratic_energy import QuadraticEnergy
 from .wiener_filter_curvature import WienerFilterCurvature