def zeropad_1501(name):
    """ Arxiv IDs after yymm=1501 are padded to 5 zeros """
    if not '/' in name:  # new ID
        yymm, num = name.split('.')
        if int(yymm) > 1500 and len(num) < 5:
            return yymm + ".0" + num
    return name