def mapped_to_chromosome(chrom):
    """
    Returns true if mapped to, eg, chr1 or X;
    false if mapped to other contig, eg GL*, MT*, hs*, M*
    """
    if chrom[0:2] in ['GL', 'MT', 'hs', 'NC'] or chrom[0:1] == 'M':
        return False
    return True
