Use str instead of basestring

args.py

@@ -34,7 +34,7 @@ def _expand_path(path):
 def _is_collection(obj):
     """Tests if an object is a collection. Strings don't count."""
 
-    if isinstance(obj, basestring):
+    if isinstance(obj, str):
         return False
 
     return hasattr(obj, '__getitem__')
@@ -395,4 +395,4 @@ flags = args.flags
 not_flags = args.not_flags
 files = args.files
 not_files = args.not_files
-copy = args.copy
+copy = args.copy