Simplify warning message generation

dstansby · dstansby · commit 4481344d4937 · 2017-08-10T11:38:31.000+01:00
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
@@ -962,9 +962,7 @@ def __init__(self, ax, *args, **kwargs):
         self.changed()  # set the colors
 
         if kwargs:
-            s = ''
-            for key, value in kwargs.items():
-                s += '"' + str(key) + '"' + ', '
+            s = ", ".join(map(repr, kwargs))
             warnings.warn('The following kwargs were not used by contour: ' +
                           s)
 
