def _pesummary_metafile_command_line_options(parser):
    """Add command line options which are specific for reading and
    manipulating pesummary metafiles

    Parameters
    ----------
    parser: object
        OptionParser instance
    """
    pesummary_group = parser.add_argument_group(
        """Options specific for reading and manipulating pesummary metafiles
-----------------------------------------------------------------"""
        )
    pesummary_group.add_argument('--compare_results', dest=
        'compare_results', nargs='+', default=None, help=
        'labels for events stored in the posterior_samples.json that you wish to compare'
        )
    pesummary_group.add_argument('--save_to_json', action='store_true',
        default=False, help='save the meta file in json format')
    return pesummary_group
