diff --git a/examples/00_misc/00_tpl_stable.py b/examples/00_misc/00_tpl_stable.py
index 4d1a89d8..474b0f55 100644
--- a/examples/00_misc/00_tpl_stable.py
+++ b/examples/00_misc/00_tpl_stable.py
@@ -40,6 +40,7 @@
    \sigma^2_{\ell_{\mathrm{up}}} &=
    C\cdot\frac{\ell_{\mathrm{up}}^{2H}}{2H}
 """
+
 import numpy as np
 
 import gstools as gs
diff --git a/examples/00_misc/01_export.py b/examples/00_misc/01_export.py
index ad754abf..e38294fe 100644
--- a/examples/00_misc/01_export.py
+++ b/examples/00_misc/01_export.py
@@ -7,6 +7,7 @@
 
 These can be viewed for example with `Paraview <https://www.paraview.org/>`__.
 """
+
 # sphinx_gallery_thumbnail_path = 'pics/paraview.png'
 import gstools as gs
 
diff --git a/examples/00_misc/02_check_rand_meth_sampling.py b/examples/00_misc/02_check_rand_meth_sampling.py
index 0b23a929..58d998b4 100644
--- a/examples/00_misc/02_check_rand_meth_sampling.py
+++ b/examples/00_misc/02_check_rand_meth_sampling.py
@@ -2,6 +2,7 @@
 Check Random Sampling
 ---------------------
 """
+
 import numpy as np
 from matplotlib import pyplot as plt
 from mpl_toolkits.mplot3d import Axes3D
diff --git a/examples/00_misc/04_herten.py b/examples/00_misc/04_herten.py
index d9e1b16e..1e1b8a23 100644
--- a/examples/00_misc/04_herten.py
+++ b/examples/00_misc/04_herten.py
@@ -30,6 +30,7 @@
 functions, since the only produce the ``herten_transmissivity.gz``
 and ``grid_dim_origin_spacing.txt``, which are already present.
 """
+
 import os
 
 import matplotlib.pyplot as plt
diff --git a/examples/00_misc/05_standalone_field.py b/examples/00_misc/05_standalone_field.py
index fb0c2082..e467f043 100644
--- a/examples/00_misc/05_standalone_field.py
+++ b/examples/00_misc/05_standalone_field.py
@@ -7,6 +7,7 @@
 In the following example we will produce 10000 random points in 4D with
 random values and plot them.
 """
+
 import numpy as np
 
 import gstools as gs
diff --git a/examples/01_random_field/03_unstr_srf_export.py b/examples/01_random_field/03_unstr_srf_export.py
index e86e6f3e..94d00952 100644
--- a/examples/01_random_field/03_unstr_srf_export.py
+++ b/examples/01_random_field/03_unstr_srf_export.py
@@ -6,6 +6,7 @@
 Normally, such a grid would be read in, but we can simply generate one and
 then create a random field at those coordinates.
 """
+
 import numpy as np
 
 import gstools as gs
diff --git a/examples/01_random_field/04_srf_merge.py b/examples/01_random_field/04_srf_merge.py
index 00aa6511..241ed079 100644
--- a/examples/01_random_field/04_srf_merge.py
+++ b/examples/01_random_field/04_srf_merge.py
@@ -6,6 +6,7 @@
 to merge two unstructured rectangular fields.
 
 """
+
 # sphinx_gallery_thumbnail_number = 2
 import numpy as np
 
diff --git a/examples/01_random_field/06_pyvista_support.py b/examples/01_random_field/06_pyvista_support.py
index c2569f98..29de8dd7 100644
--- a/examples/01_random_field/06_pyvista_support.py
+++ b/examples/01_random_field/06_pyvista_support.py
@@ -12,6 +12,7 @@
 The :any:`Field.mesh` method enables easy field creation on PyVista meshes
 used by the :any:`SRF` or :any:`Krige` class.
 """
+
 # sphinx_gallery_thumbnail_path = 'pics/GS_pyvista_cut.png'
 import pyvista as pv
 
diff --git a/examples/02_cov_model/01_basic_methods.py b/examples/02_cov_model/01_basic_methods.py
index fb9bfe7a..4c97fba8 100755
--- a/examples/02_cov_model/01_basic_methods.py
+++ b/examples/02_cov_model/01_basic_methods.py
@@ -36,6 +36,7 @@
 correlation function as demonstrated in the introductory example.
 If one of the above functions is given, the others will be determined:
 """
+
 import gstools as gs
 
 model = gs.Exponential(dim=3, var=2.0, len_scale=10, nugget=0.5)
diff --git a/examples/02_cov_model/02_aniso_rotation.py b/examples/02_cov_model/02_aniso_rotation.py
index 2a8bac78..b7459e39 100755
--- a/examples/02_cov_model/02_aniso_rotation.py
+++ b/examples/02_cov_model/02_aniso_rotation.py
@@ -6,6 +6,7 @@
 represents the isotropic case for the model.
 Nevertheless, you can provide anisotropy ratios by:
 """
+
 import gstools as gs
 
 model = gs.Gaussian(dim=3, var=2.0, len_scale=10, anis=0.5)
diff --git a/examples/02_cov_model/03_spectral_methods.py b/examples/02_cov_model/03_spectral_methods.py
index 677811a9..61c7e49b 100755
--- a/examples/02_cov_model/03_spectral_methods.py
+++ b/examples/02_cov_model/03_spectral_methods.py
@@ -23,6 +23,7 @@
 
 You can access these methods by:
 """
+
 import gstools as gs
 
 model = gs.Gaussian(dim=3, var=2.0, len_scale=10)
diff --git a/examples/02_cov_model/04_different_scales.py b/examples/02_cov_model/04_different_scales.py
index cd6f4dee..0e2e1991 100755
--- a/examples/02_cov_model/04_different_scales.py
+++ b/examples/02_cov_model/04_different_scales.py
@@ -16,6 +16,7 @@
 
 You can access it by:
 """
+
 import gstools as gs
 
 model = gs.Stable(dim=3, var=2.0, len_scale=10)
diff --git a/examples/02_cov_model/05_additional_para.py b/examples/02_cov_model/05_additional_para.py
index 02507d96..3264cec4 100755
--- a/examples/02_cov_model/05_additional_para.py
+++ b/examples/02_cov_model/05_additional_para.py
@@ -10,6 +10,7 @@
 
 This leads to the so called **stable** covariance model and we can define it by
 """
+
 import numpy as np
 
 import gstools as gs
diff --git a/examples/02_cov_model/06_fitting_para_ranges.py b/examples/02_cov_model/06_fitting_para_ranges.py
index bd3d1196..7c8f083e 100755
--- a/examples/02_cov_model/06_fitting_para_ranges.py
+++ b/examples/02_cov_model/06_fitting_para_ranges.py
@@ -6,6 +6,7 @@
 variogram data. In the following we will use the self defined stable model
 from a previous example.
 """
+
 import numpy as np
 
 import gstools as gs
diff --git a/examples/03_variogram/00_fit_variogram.py b/examples/03_variogram/00_fit_variogram.py
index 9dc1b305..7334ed2c 100644
--- a/examples/03_variogram/00_fit_variogram.py
+++ b/examples/03_variogram/00_fit_variogram.py
@@ -2,6 +2,7 @@
 Fit Variogram
 -------------
 """
+
 import numpy as np
 
 import gstools as gs
diff --git a/examples/03_variogram/01_find_best_model.py b/examples/03_variogram/01_find_best_model.py
index c0fc383f..eab031cf 100755
--- a/examples/03_variogram/01_find_best_model.py
+++ b/examples/03_variogram/01_find_best_model.py
@@ -2,6 +2,7 @@
 Finding the best fitting variogram model
 ----------------------------------------
 """
+
 import numpy as np
 from matplotlib import pyplot as plt
 
diff --git a/examples/03_variogram/02_multi_vario.py b/examples/03_variogram/02_multi_vario.py
index f893e452..71048849 100755
--- a/examples/03_variogram/02_multi_vario.py
+++ b/examples/03_variogram/02_multi_vario.py
@@ -5,6 +5,7 @@
 In this example, we demonstrate how to estimate a variogram from multiple
 fields on the same point-set that should have the same statistical properties.
 """
+
 import matplotlib.pyplot as plt
 import numpy as np
 
diff --git a/examples/03_variogram/03_directional_2d.py b/examples/03_variogram/03_directional_2d.py
index e5744cb2..460c7513 100755
--- a/examples/03_variogram/03_directional_2d.py
+++ b/examples/03_variogram/03_directional_2d.py
@@ -7,6 +7,7 @@
 
 Afterwards we will fit a model to this estimated variogram and show the result.
 """
+
 import numpy as np
 from matplotlib import pyplot as plt
 
diff --git a/examples/03_variogram/04_directional_3d.py b/examples/03_variogram/04_directional_3d.py
index 22ee7e9f..6a8b6ddf 100755
--- a/examples/03_variogram/04_directional_3d.py
+++ b/examples/03_variogram/04_directional_3d.py
@@ -7,6 +7,7 @@
 
 Afterwards we will fit a model to this estimated variogram and show the result.
 """
+
 import matplotlib.pyplot as plt
 import numpy as np
 from mpl_toolkits.mplot3d import Axes3D
diff --git a/examples/03_variogram/05_auto_fit_variogram.py b/examples/03_variogram/05_auto_fit_variogram.py
index 9c1cf2f9..2fcc7fbd 100644
--- a/examples/03_variogram/05_auto_fit_variogram.py
+++ b/examples/03_variogram/05_auto_fit_variogram.py
@@ -2,6 +2,7 @@
 Fit Variogram with automatic binning
 ------------------------------------
 """
+
 import numpy as np
 
 import gstools as gs
diff --git a/examples/03_variogram/06_auto_bin_latlon.py b/examples/03_variogram/06_auto_bin_latlon.py
index 20f6f9bc..cc248ea1 100644
--- a/examples/03_variogram/06_auto_bin_latlon.py
+++ b/examples/03_variogram/06_auto_bin_latlon.py
@@ -8,6 +8,7 @@
 
 We use a data set from 20 meteo-stations choosen randomly.
 """
+
 import numpy as np
 
 import gstools as gs
diff --git a/examples/04_vector_field/00_2d_vector_field.py b/examples/04_vector_field/00_2d_vector_field.py
index 6a6c71ac..2e722764 100644
--- a/examples/04_vector_field/00_2d_vector_field.py
+++ b/examples/04_vector_field/00_2d_vector_field.py
@@ -5,6 +5,7 @@
 As a first example we are going to generate a 2d vector field with a Gaussian
 covariance model on a structured grid:
 """
+
 import numpy as np
 
 import gstools as gs
diff --git a/examples/04_vector_field/01_3d_vector_field.py b/examples/04_vector_field/01_3d_vector_field.py
index 38a53f96..5b1872bd 100755
--- a/examples/04_vector_field/01_3d_vector_field.py
+++ b/examples/04_vector_field/01_3d_vector_field.py
@@ -6,6 +6,7 @@
 Gaussian covariance model. The mesh on which we generate the field will be
 externally defined and it will be generated by PyVista.
 """
+
 # sphinx_gallery_thumbnail_path = 'pics/GS_3d_vector_field.png'
 import pyvista as pv
 
diff --git a/examples/05_kriging/00_simple_kriging.py b/examples/05_kriging/00_simple_kriging.py
index bb83a32c..1a245b6c 100755
--- a/examples/05_kriging/00_simple_kriging.py
+++ b/examples/05_kriging/00_simple_kriging.py
@@ -27,6 +27,7 @@
 The mean of the field has to be given beforehand.
 
 """
+
 import numpy as np
 
 from gstools import Gaussian, krige
diff --git a/examples/05_kriging/01_ordinary_kriging.py b/examples/05_kriging/01_ordinary_kriging.py
index 3bc54bd9..d26254ef 100644
--- a/examples/05_kriging/01_ordinary_kriging.py
+++ b/examples/05_kriging/01_ordinary_kriging.py
@@ -27,6 +27,7 @@
 Here we use ordinary kriging in 1D (for plotting reasons) with 5 given observations/conditions.
 The estimated mean can be accessed by ``krig.mean``.
 """
+
 import numpy as np
 
 from gstools import Gaussian, krige
diff --git a/examples/05_kriging/02_pykrige_interface.py b/examples/05_kriging/02_pykrige_interface.py
index bb166d29..a6fbf03e 100755
--- a/examples/05_kriging/02_pykrige_interface.py
+++ b/examples/05_kriging/02_pykrige_interface.py
@@ -11,6 +11,7 @@
 To demonstrate the general workflow, we compare ordinary kriging of PyKrige
 with the corresponding GSTools routine in 2D:
 """
+
 import numpy as np
 from matplotlib import pyplot as plt
 from pykrige.ok import OrdinaryKriging
diff --git a/examples/05_kriging/03_compare_kriging.py b/examples/05_kriging/03_compare_kriging.py
index 12f5c43b..463faa0a 100755
--- a/examples/05_kriging/03_compare_kriging.py
+++ b/examples/05_kriging/03_compare_kriging.py
@@ -2,6 +2,7 @@
 Compare Kriging
 ---------------
 """
+
 import matplotlib.pyplot as plt
 import numpy as np
 
diff --git a/examples/05_kriging/04_extdrift_kriging.py b/examples/05_kriging/04_extdrift_kriging.py
index b9bbb54a..2e6a168a 100755
--- a/examples/05_kriging/04_extdrift_kriging.py
+++ b/examples/05_kriging/04_extdrift_kriging.py
@@ -2,6 +2,7 @@
 External Drift Kriging
 ----------------------
 """
+
 import numpy as np
 
 from gstools import SRF, Gaussian, krige
diff --git a/examples/05_kriging/05_universal_kriging.py b/examples/05_kriging/05_universal_kriging.py
index d3cf2880..5501694a 100755
--- a/examples/05_kriging/05_universal_kriging.py
+++ b/examples/05_kriging/05_universal_kriging.py
@@ -13,6 +13,7 @@
 To access only the estimated mean/drift, we provide a switch `only_mean`
 in the call routine.
 """
+
 import numpy as np
 
 from gstools import SRF, Gaussian, krige
diff --git a/examples/05_kriging/06_detrended_kriging.py b/examples/05_kriging/06_detrended_kriging.py
index b68e6502..6d20cf1d 100755
--- a/examples/05_kriging/06_detrended_kriging.py
+++ b/examples/05_kriging/06_detrended_kriging.py
@@ -2,6 +2,7 @@
 Detrended Kriging
 -----------------
 """
+
 import numpy as np
 
 from gstools import SRF, Gaussian, krige
diff --git a/examples/05_kriging/07_detrended_ordinary_kriging.py b/examples/05_kriging/07_detrended_ordinary_kriging.py
index 9a59fc33..81d01744 100755
--- a/examples/05_kriging/07_detrended_ordinary_kriging.py
+++ b/examples/05_kriging/07_detrended_ordinary_kriging.py
@@ -2,6 +2,7 @@
 Detrended Ordinary Kriging
 --------------------------
 """
+
 import numpy as np
 
 from gstools import SRF, Gaussian, krige
diff --git a/examples/05_kriging/09_pseudo_inverse.py b/examples/05_kriging/09_pseudo_inverse.py
index 9920a956..7615d888 100755
--- a/examples/05_kriging/09_pseudo_inverse.py
+++ b/examples/05_kriging/09_pseudo_inverse.py
@@ -17,6 +17,7 @@
 In the following we have two different values at the same location.
 The resulting kriging field will hold the average at this point.
 """
+
 import numpy as np
 
 from gstools import Gaussian, krige
diff --git a/examples/06_conditioned_fields/00_condition_ensemble.py b/examples/06_conditioned_fields/00_condition_ensemble.py
index 716edd20..5cc07eed 100644
--- a/examples/06_conditioned_fields/00_condition_ensemble.py
+++ b/examples/06_conditioned_fields/00_condition_ensemble.py
@@ -6,6 +6,7 @@
 with 5 given observations/conditions,
 to generate an ensemble of conditioned random fields.
 """
+
 import matplotlib.pyplot as plt
 import numpy as np
 
diff --git a/examples/06_conditioned_fields/01_2D_condition_ensemble.py b/examples/06_conditioned_fields/01_2D_condition_ensemble.py
index 4a03e66b..81f51464 100644
--- a/examples/06_conditioned_fields/01_2D_condition_ensemble.py
+++ b/examples/06_conditioned_fields/01_2D_condition_ensemble.py
@@ -4,6 +4,7 @@
 
 Let's create an ensemble of conditioned random fields in 2D.
 """
+
 import matplotlib.pyplot as plt
 import numpy as np
 
diff --git a/examples/07_transformations/00_log_normal.py b/examples/07_transformations/00_log_normal.py
index 3d2f4532..d44c1627 100755
--- a/examples/07_transformations/00_log_normal.py
+++ b/examples/07_transformations/00_log_normal.py
@@ -6,6 +6,7 @@
 
 See :any:`transform.normal_to_lognormal`
 """
+
 import gstools as gs
 
 # structured field with a size of 100x100 and a grid-size of 1x1
diff --git a/examples/07_transformations/01_binary.py b/examples/07_transformations/01_binary.py
index a403abb7..125e29d0 100755
--- a/examples/07_transformations/01_binary.py
+++ b/examples/07_transformations/01_binary.py
@@ -8,6 +8,7 @@
 
 See :any:`transform.binary`
 """
+
 import gstools as gs
 
 # structured field with a size of 100x100 and a grid-size of 1x1
diff --git a/examples/07_transformations/02_discrete.py b/examples/07_transformations/02_discrete.py
index 268cc960..48f67a2d 100755
--- a/examples/07_transformations/02_discrete.py
+++ b/examples/07_transformations/02_discrete.py
@@ -9,6 +9,7 @@
 
 See :any:`transform.discrete`
 """
+
 import numpy as np
 
 import gstools as gs
diff --git a/examples/07_transformations/03_zinn_harvey.py b/examples/07_transformations/03_zinn_harvey.py
index 01e65790..fad1fb64 100755
--- a/examples/07_transformations/03_zinn_harvey.py
+++ b/examples/07_transformations/03_zinn_harvey.py
@@ -9,6 +9,7 @@
 
 See :any:`transform.zinnharvey`
 """
+
 import gstools as gs
 
 # structured field with a size of 100x100 and a grid-size of 1x1
diff --git a/examples/07_transformations/04_bimodal.py b/examples/07_transformations/04_bimodal.py
index 8234a486..4dd6fb29 100755
--- a/examples/07_transformations/04_bimodal.py
+++ b/examples/07_transformations/04_bimodal.py
@@ -11,6 +11,7 @@
 
 See: :any:`transform.normal_to_arcsin` and :any:`transform.normal_to_uquad`
 """
+
 import gstools as gs
 
 # structured field with a size of 100x100 and a grid-size of 1x1
diff --git a/examples/07_transformations/05_combinations.py b/examples/07_transformations/05_combinations.py
index fb27c5e6..1fbe367e 100755
--- a/examples/07_transformations/05_combinations.py
+++ b/examples/07_transformations/05_combinations.py
@@ -15,6 +15,7 @@
 
 If you don't specify `field` and `store` everything happens inplace.
 """
+
 # sphinx_gallery_thumbnail_number = 1
 import gstools as gs
 
diff --git a/examples/08_geo_coordinates/00_field_generation.py b/examples/08_geo_coordinates/00_field_generation.py
index b7b3748a..5b1a6fca 100755
--- a/examples/08_geo_coordinates/00_field_generation.py
+++ b/examples/08_geo_coordinates/00_field_generation.py
@@ -16,6 +16,7 @@
 To generate the field, we simply pass ``(lat, lon)`` as the position tuple
 to the :any:`SRF` class.
 """
+
 import numpy as np
 
 import gstools as gs
diff --git a/examples/08_geo_coordinates/01_dwd_krige.py b/examples/08_geo_coordinates/01_dwd_krige.py
index 44b9f28c..3c17fb7e 100755
--- a/examples/08_geo_coordinates/01_dwd_krige.py
+++ b/examples/08_geo_coordinates/01_dwd_krige.py
@@ -15,6 +15,7 @@
 In order to keep the number of dependecies low, the calls of both functions
 shown beneath are commented out.
 """
+
 # sphinx_gallery_thumbnail_number = 2
 import matplotlib.pyplot as plt
 import numpy as np
diff --git a/examples/09_spatio_temporal/03_geographic_coordinates.py b/examples/09_spatio_temporal/03_geographic_coordinates.py
index 56684a94..b1cfbff6 100644
--- a/examples/09_spatio_temporal/03_geographic_coordinates.py
+++ b/examples/09_spatio_temporal/03_geographic_coordinates.py
@@ -18,6 +18,7 @@
 
 We will set a spatial length-scale of `1000` and a time length-scale of `100` days.
 """
+
 import numpy as np
 
 import gstools as gs
diff --git a/examples/10_normalizer/00_lognormal_kriging.py b/examples/10_normalizer/00_lognormal_kriging.py
index b7bf4a8a..9880bc37 100644
--- a/examples/10_normalizer/00_lognormal_kriging.py
+++ b/examples/10_normalizer/00_lognormal_kriging.py
@@ -14,6 +14,7 @@
 
 In this example we will use ordinary kriging.
 """
+
 import numpy as np
 
 import gstools as gs
diff --git a/examples/10_normalizer/01_auto_fit.py b/examples/10_normalizer/01_auto_fit.py
index 80a49569..71ad1385 100644
--- a/examples/10_normalizer/01_auto_fit.py
+++ b/examples/10_normalizer/01_auto_fit.py
@@ -18,6 +18,7 @@
 We will generate the "original" field on a 60x60 mesh, from which we will take
 samples in order to pretend a situation of data-scarcity.
 """
+
 import matplotlib.pyplot as plt
 import numpy as np
 
diff --git a/examples/10_normalizer/02_compare.py b/examples/10_normalizer/02_compare.py
index 24f7c9f8..2dd74488 100644
--- a/examples/10_normalizer/02_compare.py
+++ b/examples/10_normalizer/02_compare.py
@@ -6,6 +6,7 @@
 
 But first, we define a convenience routine and make some imports as always.
 """
+
 import matplotlib.pyplot as plt
 import numpy as np
 
diff --git a/setup.py b/setup.py
index f465ffd4..b27548a9 100644
--- a/setup.py
+++ b/setup.py
@@ -1,4 +1,5 @@
 """GSTools: A geostatistical toolbox."""
+
 import os
 
 import numpy as np
diff --git a/src/gstools/__init__.py b/src/gstools/__init__.py
index 6d62d558..11e63a2b 100644
--- a/src/gstools/__init__.py
+++ b/src/gstools/__init__.py
@@ -129,6 +129,7 @@
    DEGREE_SCALE
    RADIAN_SCALE
 """
+
 # Hooray!
 from gstools import (
     config,
diff --git a/src/gstools/config.py b/src/gstools/config.py
index f0a87bb6..24ce20c7 100644
--- a/src/gstools/config.py
+++ b/src/gstools/config.py
@@ -4,6 +4,7 @@
 .. currentmodule:: gstools.config
 
 """
+
 NUM_THREADS = None
 
 # pylint: disable=W0611
diff --git a/src/gstools/covmodel/base.py b/src/gstools/covmodel/base.py
index be530075..23e19881 100644
--- a/src/gstools/covmodel/base.py
+++ b/src/gstools/covmodel/base.py
@@ -8,6 +8,7 @@
 .. autosummary::
    CovModel
 """
+
 # pylint: disable=C0103, R0201, E1101, C0302, W0613
 import copy
 
diff --git a/src/gstools/covmodel/fit.py b/src/gstools/covmodel/fit.py
index dc2d5a3a..b420be70 100755
--- a/src/gstools/covmodel/fit.py
+++ b/src/gstools/covmodel/fit.py
@@ -8,6 +8,7 @@
 .. autosummary::
    fit_variogram
 """
+
 # pylint: disable=C0103, W0632
 import numpy as np
 from scipy.optimize import curve_fit
@@ -308,9 +309,11 @@ def _pre_init_guess(model, init_guess, mean_x=1.0, mean_y=1.0):
     for opt in model.opt_arg:
         init_guess.setdefault(
             opt,
-            default_arg_from_bounds(bnd[opt])
-            if default
-            else getattr(model, opt),
+            (
+                default_arg_from_bounds(bnd[opt])
+                if default
+                else getattr(model, opt)
+            ),
         )
     # convert all init guesses to float (except "anis")
     for arg in model.iso_arg:
diff --git a/src/gstools/covmodel/models.py b/src/gstools/covmodel/models.py
index a2aaf6a3..ab94e279 100644
--- a/src/gstools/covmodel/models.py
+++ b/src/gstools/covmodel/models.py
@@ -20,6 +20,7 @@
    SuperSpherical
    JBessel
 """
+
 # pylint: disable=C0103, E1101, R0201
 import warnings
 
diff --git a/src/gstools/covmodel/plot.py b/src/gstools/covmodel/plot.py
index 334ccbe2..32148c14 100644
--- a/src/gstools/covmodel/plot.py
+++ b/src/gstools/covmodel/plot.py
@@ -24,6 +24,7 @@
    plot_spectral_density
    plot_spectral_rad_pdf
 """
+
 # pylint: disable=C0103, C0415, E1130
 import numpy as np
 
diff --git a/src/gstools/covmodel/tpl_models.py b/src/gstools/covmodel/tpl_models.py
index 5e980760..b728e7b9 100644
--- a/src/gstools/covmodel/tpl_models.py
+++ b/src/gstools/covmodel/tpl_models.py
@@ -11,6 +11,7 @@
    TPLStable
    TPLSimple
 """
+
 # pylint: disable=C0103, E1101
 import warnings
 
diff --git a/src/gstools/field/base.py b/src/gstools/field/base.py
index b0e5efeb..2006b858 100755
--- a/src/gstools/field/base.py
+++ b/src/gstools/field/base.py
@@ -8,6 +8,7 @@
 .. autosummary::
    Field
 """
+
 # pylint: disable=C0103, C0415
 from collections.abc import Iterable
 from copy import copy
diff --git a/src/gstools/field/cond_srf.py b/src/gstools/field/cond_srf.py
index 385216ba..c3e03fe2 100644
--- a/src/gstools/field/cond_srf.py
+++ b/src/gstools/field/cond_srf.py
@@ -8,6 +8,7 @@
 .. autosummary::
    CondSRF
 """
+
 # pylint: disable=C0103, W0231, W0221, W0222, E1102
 
 import numpy as np
diff --git a/src/gstools/field/generator.py b/src/gstools/field/generator.py
index 571c9733..5beab10d 100644
--- a/src/gstools/field/generator.py
+++ b/src/gstools/field/generator.py
@@ -12,6 +12,7 @@
    RandMeth
    IncomprRandMeth
 """
+
 # pylint: disable=C0103, W0222, C0412, W0231
 import warnings
 from abc import ABC, abstractmethod
diff --git a/src/gstools/field/plot.py b/src/gstools/field/plot.py
index d06a22a1..ab28c974 100644
--- a/src/gstools/field/plot.py
+++ b/src/gstools/field/plot.py
@@ -9,6 +9,7 @@
    plot_field
    plot_vec_field
 """
+
 # pylint: disable=C0103, W0613, E1101
 import numpy as np
 from scipy import interpolate as inter
diff --git a/src/gstools/field/srf.py b/src/gstools/field/srf.py
index a8a1e575..d88e46c0 100644
--- a/src/gstools/field/srf.py
+++ b/src/gstools/field/srf.py
@@ -8,6 +8,7 @@
 .. autosummary::
    SRF
 """
+
 # pylint: disable=C0103, W0221, E1102
 
 import numpy as np
diff --git a/src/gstools/field/tools.py b/src/gstools/field/tools.py
index 4b128d8a..dfa2e3c6 100644
--- a/src/gstools/field/tools.py
+++ b/src/gstools/field/tools.py
@@ -10,6 +10,7 @@
    to_vtk_helper
    generate_on_mesh
 """
+
 # pylint: disable=W0212, C0415
 import meshio
 import numpy as np
diff --git a/src/gstools/field/upscaling.py b/src/gstools/field/upscaling.py
index 6dcbaa7b..857bfc45 100644
--- a/src/gstools/field/upscaling.py
+++ b/src/gstools/field/upscaling.py
@@ -11,6 +11,7 @@
    var_coarse_graining
    var_no_scaling
 """
+
 # pylint: disable=W0613
 import warnings
 
diff --git a/src/gstools/krige/__init__.py b/src/gstools/krige/__init__.py
index bb3ef699..66d03246 100644
--- a/src/gstools/krige/__init__.py
+++ b/src/gstools/krige/__init__.py
@@ -16,6 +16,7 @@
    ExtDrift
    Detrended
 """
+
 from gstools.krige.base import Krige
 from gstools.krige.methods import (
     Detrended,
diff --git a/src/gstools/krige/base.py b/src/gstools/krige/base.py
index 75bb7b10..49a4f62f 100755
--- a/src/gstools/krige/base.py
+++ b/src/gstools/krige/base.py
@@ -8,6 +8,7 @@
 .. autosummary::
    Krige
 """
+
 # pylint: disable=C0103, W0221, E1102, R0201, C0412
 import collections
 
diff --git a/src/gstools/krige/methods.py b/src/gstools/krige/methods.py
index b258a02d..19ffed56 100644
--- a/src/gstools/krige/methods.py
+++ b/src/gstools/krige/methods.py
@@ -12,6 +12,7 @@
    ExtDrift
    Detrended
 """
+
 # pylint: disable=C0103
 from gstools.krige.base import Krige
 
diff --git a/src/gstools/krige/tools.py b/src/gstools/krige/tools.py
index e3112ae4..62926595 100644
--- a/src/gstools/krige/tools.py
+++ b/src/gstools/krige/tools.py
@@ -9,6 +9,7 @@
    set_condition
    get_drift_functions
 """
+
 # pylint: disable=C0103
 from itertools import combinations_with_replacement
 
diff --git a/src/gstools/normalizer/base.py b/src/gstools/normalizer/base.py
index 0072d6a9..4a8477c6 100644
--- a/src/gstools/normalizer/base.py
+++ b/src/gstools/normalizer/base.py
@@ -8,6 +8,7 @@
 .. autosummary::
    Normalizer
 """
+
 # pylint: disable=R0201
 import warnings
 
diff --git a/src/gstools/normalizer/methods.py b/src/gstools/normalizer/methods.py
index f66cfd19..a46dc230 100644
--- a/src/gstools/normalizer/methods.py
+++ b/src/gstools/normalizer/methods.py
@@ -13,6 +13,7 @@
    Modulus
    Manly
 """
+
 # pylint: disable=E1101
 import numpy as np
 
diff --git a/src/gstools/normalizer/tools.py b/src/gstools/normalizer/tools.py
index 7a5237b7..3e395d29 100644
--- a/src/gstools/normalizer/tools.py
+++ b/src/gstools/normalizer/tools.py
@@ -9,6 +9,7 @@
    apply_mean_norm_trend
    remove_trend_norm_mean
 """
+
 import numpy as np
 
 from gstools.normalizer.base import Normalizer
diff --git a/src/gstools/random/rng.py b/src/gstools/random/rng.py
index 4f698557..ad78a0c6 100644
--- a/src/gstools/random/rng.py
+++ b/src/gstools/random/rng.py
@@ -8,6 +8,7 @@
 .. autosummary::
    RNG
 """
+
 # pylint: disable=E1101
 import emcee as mc
 import numpy as np
diff --git a/src/gstools/tools/export.py b/src/gstools/tools/export.py
index 3e522c92..38254ceb 100644
--- a/src/gstools/tools/export.py
+++ b/src/gstools/tools/export.py
@@ -13,6 +13,7 @@
    to_vtk_structured
    to_vtk_unstructured
 """
+
 # pylint: disable=C0103, E1101
 import numpy as np
 from pyevtk.hl import gridToVTK, pointsToVTK
diff --git a/src/gstools/tools/geometric.py b/src/gstools/tools/geometric.py
index 57604fbb..55408965 100644
--- a/src/gstools/tools/geometric.py
+++ b/src/gstools/tools/geometric.py
@@ -29,6 +29,7 @@
    chordal_to_great_circle
    great_circle_to_chordal
 """
+
 # pylint: disable=C0103
 import numpy as np
 
diff --git a/src/gstools/tools/misc.py b/src/gstools/tools/misc.py
index 068200b7..aaba1501 100755
--- a/src/gstools/tools/misc.py
+++ b/src/gstools/tools/misc.py
@@ -10,6 +10,7 @@
    list_format
    eval_func
 """
+
 # pylint: disable=C0103, C0415
 import numpy as np
 
diff --git a/src/gstools/tools/special.py b/src/gstools/tools/special.py
index c48887ea..1457b736 100644
--- a/src/gstools/tools/special.py
+++ b/src/gstools/tools/special.py
@@ -14,6 +14,7 @@
    tpl_exp_spec_dens
    tpl_gau_spec_dens
 """
+
 # pylint: disable=C0103, E1101
 import numpy as np
 from scipy import special as sps
diff --git a/src/gstools/transform/array.py b/src/gstools/transform/array.py
index 30c92bb6..87564edf 100644
--- a/src/gstools/transform/array.py
+++ b/src/gstools/transform/array.py
@@ -18,6 +18,7 @@
    array_to_arcsin
    array_to_uquad
 """
+
 # pylint: disable=C0103, C0123, R0911
 from warnings import warn
 
diff --git a/src/gstools/transform/field.py b/src/gstools/transform/field.py
index 110232f6..4a281564 100644
--- a/src/gstools/transform/field.py
+++ b/src/gstools/transform/field.py
@@ -26,6 +26,7 @@
    normal_to_arcsin
    normal_to_uquad
 """
+
 # pylint: disable=C0103, C0123, R0911, R1735
 import numpy as np
 
diff --git a/src/gstools/variogram/binning.py b/src/gstools/variogram/binning.py
index e8e42f38..86d4fdc2 100644
--- a/src/gstools/variogram/binning.py
+++ b/src/gstools/variogram/binning.py
@@ -8,6 +8,7 @@
 .. autosummary::
    standard_bins
 """
+
 import numpy as np
 
 from gstools.tools import RADIAN_SCALE
diff --git a/src/gstools/variogram/variogram.py b/src/gstools/variogram/variogram.py
index a08f1fbf..afcf336f 100644
--- a/src/gstools/variogram/variogram.py
+++ b/src/gstools/variogram/variogram.py
@@ -9,6 +9,7 @@
    vario_estimate
    vario_estimate_axis
 """
+
 # pylint: disable=C0412
 import numpy as np
 
diff --git a/tests/test_condition.py b/tests/test_condition.py
index e6b0c0cc..8d5d0535 100644
--- a/tests/test_condition.py
+++ b/tests/test_condition.py
@@ -1,4 +1,5 @@
 """This is the unittest of CondSRF class."""
+
 import unittest
 from copy import copy
 
diff --git a/tests/test_covmodel.py b/tests/test_covmodel.py
index b4344cc2..a2729dd6 100644
--- a/tests/test_covmodel.py
+++ b/tests/test_covmodel.py
@@ -1,6 +1,7 @@
 """
 This is the unittest of CovModel class.
 """
+
 import unittest
 
 import numpy as np
diff --git a/tests/test_export.py b/tests/test_export.py
index 9bd6dd41..a3efdede 100644
--- a/tests/test_export.py
+++ b/tests/test_export.py
@@ -1,5 +1,6 @@
 """Test the PyVista/VTK export methods
 """
+
 import os
 import shutil
 import tempfile
diff --git a/tests/test_transform.py b/tests/test_transform.py
index eb2980e2..abc5505b 100644
--- a/tests/test_transform.py
+++ b/tests/test_transform.py
@@ -1,4 +1,5 @@
 """This is the unittest of the transform submodule."""
+
 import unittest
 
 import numpy as np