LGTM, but after applying to all 3, leave open (or open new issue) to replace patch in 3.6 (before beta 1). Change signature to *items. That will automatically make a single string become a len 1 tuple. For selection (list the 4 selops and) add a note. "For back compatibility, one may also pass a single tuple (or list?) of items." and Version Changed. For 4 derivatives, 'See selection.' In the code, instead add (untested): if len(items) == 1: # Remove after deprecation. item0 = items[0] if not isinstance(items[0], isinstance(str)): raise DeprecationWarning( <level arg> "The option of passing multiple items as a tuple " "rather than as multiple items is deprecated and " "will be removed in 2020 or later.") items = items0 # or more processing if lists were allowed Revise test accordingly.