def chrom_to_num(label):
    """
    Transforms a chromosome label into its numeric correspondence:
    Chrom 1:22 without changes
    Chrom X -> 23
    Chrom Y -> 24
    :param label:
    :return:
    """
    vid = label
    if label == 'X':
        vid = '23'
    elif label == 'Y':
        vid = '24'
    return vid