def get_cutoff_class(sample):
    """
    Identify which set of cutoffs to use when classifying a given variant call

    Arguments
    ---------
    sample : namedtuple('Metrics')
        Row from variant metrics table

    Returns
    -------
    (source, svtype) : (str, str)
        Key to cutoffs table
    """

    if sample.sources == 'depth' and sample.svtype == 'DEL':
        return ('depth', 'DEL')
    elif sample.sources == 'depth' and sample.svtype == 'DUP':
        return ('depth', 'DUP')
    elif (sample.svtype in 'DEL DUP'.split() and sample.svsize >= 1000):
        return ('pesr', 'CNV')
    else:
        return ('pesr', 'SV')