def write_bdfs_list(bdf_files, cards, size, is_double, is_long_ids):
    """writes a list by ifile"""
    assert isinstance(cards, list), cards
    if is_long_ids:
        for card in cards:
            bdf_files[card.ifile].write_card_16(size, is_double)
    else:
        for card in cards:
            bdf_files[card.ifile].write_card(size, is_double)
