Use getfullargspec on python3

Prefere this over getargspec which will be removed in 3.6. This is the least intrusive change however getfullargspec has been deprecated too. Post 2.0 we should rewrite the code to use signature instead

boilerplate.py

@@ -209,7 +209,12 @@ def format_value(value):
                 mappable = ''
 
             # Get argspec of wrapped function
-            args, varargs, varkw, defaults = inspect.getargspec(getattr(Axes, func))
+            if six.PY2:
+                args, varargs, varkw, defaults = inspect.getargspec(
+                                                    getattr(Axes, func))
+            else:
+                (args, varargs, varkw, defaults, kwonlyargs, kwonlydefs,
+                    annotations) = inspect.getfullargspec(getattr(Axes, func))
             args.pop(0)  # remove 'self' argument
             if defaults is None:
                 defaults = ()

lib/matplotlib/artist.py

@@ -1110,7 +1110,11 @@ def _get_setters_and_targets(self):
             o = getattr(self.o, name)
             if not six.callable(o):
                 continue
-            if len(inspect.getargspec(o)[0]) < 2:
+            if six.PY2:
+                nargs = len(inspect.getargspec(o)[0])
+            else:
+                nargs = len(inspect.getfullargspec(o)[0])
+            if nargs < 2:
                 continue
             func = o
             if self.is_alias(func):

lib/matplotlib/patches.py

@@ -1781,7 +1781,11 @@ def _pprint_styles(_styles):
     _table = [["Class", "Name", "Attrs"]]
 
     for name, cls in sorted(_styles.items()):
-        args, varargs, varkw, defaults = inspect.getargspec(cls.__init__)
+        if six.PY2:
+            args, varargs, varkw, defaults = inspect.getargspec(cls.__init__)
+        else:
+            (args, varargs, varkw, defaults, kwonlyargs, kwonlydefs, 
+                annotations) = inspect.getfullargspec(cls.__init__)
         if defaults:
             args = [(argname, argdefault)
                     for argname, argdefault in zip(args[1:], defaults)]