Update _base.py

Fixing if condition.

Author: pedrompecanha

lib/matplotlib/axes/_base.py

@@ -3285,7 +3285,7 @@ def ticklabel_format(self, *, axis='both', style=None, scilimits=None,
                 raise ValueError("scilimits must be a sequence of 2 integers"
                                  ) from err
         STYLES = {'sci': True, 'scientific': True, 'plain': False}
-        if style == None:
+        if style is None:
             is_sci_style = False
         else:
             is_sci_style = _api.check_getitem(STYLES, style=style)