diff --git a/examples/plot_two_tallies_combined.py b/examples/plot_two_tallies_combined.py
index e8383d9..10d6c87 100644
--- a/examples/plot_two_tallies_combined.py
+++ b/examples/plot_two_tallies_combined.py
@@ -38,18 +38,18 @@
     # work with older versions of openmc
     source_n = openmc.Source()
     source_p = openmc.Source()
-    
+
 source_n.space = openmc.stats.Point((200, 0, 0))
 source_n.angle = openmc.stats.Isotropic()
 source_n.energy = openmc.stats.Discrete([0.1e6], [1])
 source_n.strength = 1
-source_n.particle='neutron'
+source_n.particle = "neutron"
 
 source_p.space = openmc.stats.Point((-200, 0, 0))
 source_p.angle = openmc.stats.Isotropic()
 source_p.energy = openmc.stats.Discrete([10e6], [1])
 source_p.strength = 10
-source_p.particle='photon'
+source_p.particle = "photon"
 
 my_settings.source = [source_n, source_p]
 
@@ -101,7 +101,7 @@
 )
 plot.title.set_text("neutron heating")
 plot.figure.savefig("neutron_regular_mesh_plotter.png")
-print('written file neutron_regular_mesh_plotter.png')
+print("written file neutron_regular_mesh_plotter.png")
 
 plot = plot_mesh_tally(
     tally=[my_mesh_tally_photon],
@@ -110,7 +110,7 @@
 )
 plot.title.set_text("photon heating")
 plot.figure.savefig("photon_regular_mesh_plotter.png")
-print('written file photon_regular_mesh_plotter.png')
+print("written file photon_regular_mesh_plotter.png")
 
 plot = plot_mesh_tally(
     tally=[my_mesh_tally_photon, my_mesh_tally_neutron],
@@ -119,4 +119,4 @@
 )
 plot.title.set_text("photon and neutron heating")
 plot.figure.savefig("photon_and_neutron_regular_mesh_plotter.png")
-print('written file photon_and_neutron_regular_mesh_plotter.png')
+print("written file photon_and_neutron_regular_mesh_plotter.png")
diff --git a/src/openmc_regular_mesh_plotter/core.py b/src/openmc_regular_mesh_plotter/core.py
index 7247e91..6f219f8 100644
--- a/src/openmc_regular_mesh_plotter/core.py
+++ b/src/openmc_regular_mesh_plotter/core.py
@@ -108,12 +108,16 @@ def plot_mesh_tally(
             # TODO check the tallies use the same mesh
             mesh_ids.append(mesh.id)
         if not all(i == mesh_ids[0] for i in mesh_ids):
-            raise ValueError(f'mesh ids {mesh_ids} are different, please use same mesh when combining tallies')
+            raise ValueError(
+                f"mesh ids {mesh_ids} are different, please use same mesh when combining tallies"
+            )
     else:
         mesh = tally.find_filter(filter_type=openmc.MeshFilter).mesh
 
     if isinstance(mesh, openmc.CylindricalMesh):
-        raise NotImplemented(f"Only RegularMesh are supported, not {type(mesh)}, try the openmc_cylindrical_mesh_plotter package available at https://github.com/fusion-energy/openmc_cylindrical_mesh_plotter/")
+        raise NotImplemented(
+            f"Only RegularMesh are supported, not {type(mesh)}, try the openmc_cylindrical_mesh_plotter package available at https://github.com/fusion-energy/openmc_cylindrical_mesh_plotter/"
+        )
     if not isinstance(mesh, openmc.RegularMesh):
         raise NotImplemented(f"Only RegularMesh are supported, not {type(mesh)}")
 
@@ -145,7 +149,6 @@ def plot_mesh_tally(
     default_imshow_kwargs.update(kwargs)
 
     if isinstance(tally, typing.Sequence):
-        
         for counter, one_tally in enumerate(tally):
             new_data = _get_tally_data(
                 scaling_factor,
@@ -155,11 +158,11 @@ def plot_mesh_tally(
                 value,
                 volume_normalization,
                 score,
-                slice_index
+                slice_index,
             )
             if counter == 0:
                 data = np.zeros(shape=new_data.shape)
-            data=data+new_data
+            data = data + new_data
     else:  # single tally
         data = _get_tally_data(
             scaling_factor,
@@ -169,7 +172,7 @@ def plot_mesh_tally(
             value,
             volume_normalization,
             score,
-            slice_index
+            slice_index,
         )
 
     im = axes.imshow(data, extent=(x_min, x_max, y_min, y_max), **default_imshow_kwargs)
@@ -295,17 +298,10 @@ def get_index_where(self, value: float, basis: str = "xy"):
 
     return slice_index
 
+
 def _get_tally_data(
-        scaling_factor,
-        mesh,
-        basis,
-        tally,
-        value,
-        volume_normalization,
-        score,
-        slice_index
+    scaling_factor, mesh, basis, tally, value, volume_normalization, score, slice_index
 ):
-        
     # if score is not specified and tally has a single score then we know which score to use
     if score is None:
         if len(tally.scores) == 1:
@@ -316,8 +312,6 @@ def _get_tally_data(
 
     tally_slice = tally.get_slice(scores=[score])
 
-    
-
     if 1 in mesh.dimension:
         index_of_2d = mesh.dimension.index(1)
         axis_of_2d = {0: "x", 1: "y", 2: "z"}[index_of_2d]
@@ -340,7 +334,6 @@ def _get_tally_data(
 
     # if len(tally_data.shape) == 3:
     if mesh.n_dimension == 3:
-
         if basis == "xz":
             slice_data = tally_data[:, slice_index, :]
             data = np.flip(np.rot90(slice_data, -1))
@@ -362,4 +355,4 @@ def _get_tally_data(
 
     if scaling_factor:
         data = data * scaling_factor
-    return data
\ No newline at end of file
+    return data
diff --git a/tests/test_units.py b/tests/test_units.py
index e4fceb1..b441cb8 100644
--- a/tests/test_units.py
+++ b/tests/test_units.py
@@ -170,7 +170,9 @@ def test_plot_two_mesh_tallies(model):
         tally_result_2 = statepoint.get_tally(name="mesh-tal-2")
 
     plot = plot_mesh_tally(
-        tally=[tally_result_1, tally_result_2], basis="yz", slice_index=0  # max value of slice selected
+        tally=[tally_result_1, tally_result_2],
+        basis="yz",
+        slice_index=0,  # max value of slice selected
     )
 
     plot = plot_mesh_tally(tally=[tally_result_1, tally_result_2], basis="yz")
@@ -194,4 +196,5 @@ def test_plot_two_mesh_tallies(model):
     assert plot.get_xlim() == (-2.0, 2.5)  # note that units are in m
     assert plot.get_ylim() == (-3.0, 3.5)
 
+
 # todo catch errors when 2d mesh used and 1d axis selected for plotting'