@classmethod<EOL><INDENT>def arg_xaxis(cls, parser):<DEDENT>
group = super(TimeDomainProduct, cls).arg_xaxis(parser)<EOL>group.add_argument('<STR_LIT>', type=to_gps,<EOL>help='<STR_LIT>'<EOL>'<STR_LIT>')<EOL>return group<EOL>
Add an `~argparse.ArgumentGroup` for X-axis options.

        This method includes the standard X-axis options, as well as a new
        ``--epoch`` option for the time axis.