minor: code formatting

Author: ecobost

src/spikeinterface/widgets/unit_waveforms_density_map.py

@@ -168,16 +168,10 @@ def plot_matplotlib(self, data_plot, **backend_kwargs):
 
         dp = to_attr(data_plot)
 
-        if backend_kwargs["axes"] is not None or backend_kwargs["ax"] is not None:
-            self.figure, self.axes, self.ax = make_mpl_figure(**backend_kwargs)
-        else:
-            if dp.same_axis:
-                num_axes = 1
-            else:
-                num_axes = len(dp.unit_ids)
+        if backend_kwargs['axes'] is None and backend_kwargs['ax'] is None:
             backend_kwargs["ncols"] = 1
-            backend_kwargs["num_axes"] = num_axes
-            self.figure, self.axes, self.ax = make_mpl_figure(**backend_kwargs)
+            backend_kwargs["num_axes"] = 1 if dp.same_axis else len(dp.unit_ids)
+        self.figure, self.axes, self.ax = make_mpl_figure(**backend_kwargs)
 
         if dp.same_axis:
             ax = self.ax