pep8 fix.

Author: dcherian

xarray/plot/facetgrid.py

@@ -505,7 +505,8 @@ def map(self, func, *args, **kwargs):
                 maybe_mappable = func(*innerargs, **kwargs)
                 # TODO: is there a better way to verify that an artist is mappable?
                 # https://stackoverflow.com/questions/33023036/is-it-possible-to-detect-if-a-matplotlib-artist-is-a-mappable-suitable-for-use-w#33023522
-                if maybe_mappable and hasattr(maybe_mappable, 'autoscale_None'):
+                if (maybe_mappable and
+                   hasattr(maybe_mappable, 'autoscale_None')):
                     self._mappables.append(maybe_mappable)
 
         self._finalize_grid(*args[:2])