def verify_metric_calculation_options(opts, parser):
    """
    Parses the metric calculation options given and verifies that they are
    correct.

    Parameters
    ----------
    opts : argparse.Values instance
        Result of parsing the input options with OptionParser
    parser : object
        The OptionParser instance.
    """
    if not opts.pn_order:
        parser.error('Must supply --pn-order')
