letters:         Fix description; lowercase and uppercase are strings, not         functions!  Noted by Randall Hopper <aa8vb@yahoo.com>.
letters:
        Fix description; lowercase and uppercase are strings, not
        functions!  Noted by Randall Hopper <aa8vb@yahoo.com>.

maketrans():
        Minor markup nits in description.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator