unify API in regards to column-vs-columns

pandas/core/frame.py

@@ -2149,10 +2149,10 @@ def duplicated(self, cols=None, take_last=False):
     #----------------------------------------------------------------------
     # Sorting
 
-    def sort(self, column=None, axis=0, ascending=True):
+    def sort(self, columns=None, axis=0, ascending=True):
         """
         Sort DataFrame either by labels (along either axis) or by the values in
-        a column
+        column(s)
 
         Parameters
         ----------
@@ -2168,7 +2168,7 @@ def sort(self, column=None, axis=0, ascending=True):
         -------
         sorted : DataFrame
         """
-        return self.sort_index(by=column, axis=axis, ascending=ascending)
+        return self.sort_index(by=columns, axis=axis, ascending=ascending)
 
     def sort_index(self, axis=0, by=None, ascending=True):
         """