Update documentation in case no figure is saved

Zybulon · Zybulon · commit 3339983e3d99 · 2024-02-10T11:02:37.000+01:00
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
@@ -3230,7 +3230,8 @@ def save_figure(self, *args):
         Returns
         -------
         str or `None`
-            The filepath of the saved figure. For GTK4 and Web backends it returns None.
+            The filepath of the saved figure. For GTK4 and WebAgg backends it returns `None`.
+            Returns `None` if figure is not saved.
         """
         raise NotImplementedError
 
