Merge pull request matplotlib#2333 from andreabedini/patch-3

Fix wrong syntax for assert

Author: pelson

lib/matplotlib/docstring.py

@@ -33,8 +33,8 @@ def some_function(x):
         "%s %s wrote the Raven"
     """
     def __init__(self, *args, **kwargs):
-        assert (not (args and kwargs),
-                "Only positional or keyword args are allowed")
+        assert not (args and kwargs), \
+                "Only positional or keyword args are allowed"
         self.params = args or kwargs
 
     def __call__(self, func):