Fix: positional argument specifiers are required by Python 2.6

cgohlke · cgohlke · commit 7cdd61ff1118 · 2012-12-11T23:16:05.000-08:00
diff --git a/lib/matplotlib/backends/backend_tkagg.py b/lib/matplotlib/backends/backend_tkagg.py
@@ -467,7 +467,7 @@ def _get_key(self, event):
             # note, shift is not added to the keys as this is already accounted for
             for bitmask, prefix, key_name in modifiers:
                 if event.state & (1 << bitmask) and key_name not in key:
-                    key = '{}+{}'.format(prefix, key)
+                    key = '{0}+{1}'.format(prefix, key)
 
         return key
 
