'Return a comma-separated list of option strings & metavariables.'

def format_option_strings(self, option):

    if option.takes_value():
        metavar = (option.metavar or option.dest.upper())
        short_opts = [(self._short_opt_fmt % (sopt, metavar)) for sopt in option._short_opts]
        long_opts = [(self._long_opt_fmt % (lopt, metavar)) for lopt in option._long_opts]
    else:
        short_opts = option._short_opts
        long_opts = option._long_opts
    if self.short_first:
        opts = (short_opts + long_opts)
    else:
        opts = (long_opts + short_opts)
    return ',    '.join(opts)
