Check if copy number changes match the expected svtype.

def _check_copy_number_changes(svtype, cn, minor_cn, data):
    """Check if copy number changes match the expected svtype.
    """
    if svtype == "LOH" and minor_cn == 0:
        return svtype
    elif svtype == "amplification" and cn > dd.get_ploidy(data):
        return svtype
    else:
        return "std"