Return an individual member definition formatted as an RST glossary
        entry, wrapped to fit within 78 columns.

def _member_def(self, member):
        """
        Return an individual member definition formatted as an RST glossary
        entry, wrapped to fit within 78 columns.
        """
        member_docstring = textwrap.dedent(member.docstring).strip()
        member_docstring = textwrap.fill(
            member_docstring, width=78, initial_indent=' '*4,
            subsequent_indent=' '*4
        )
        return '%s\n%s\n' % (member.name, member_docstring)