def __get_default_structure_ids():
    '''COMMENT'''
    if len(__DEFAULT_STRUCTURE_IDS) == 0:
        filename = get_file('default_structures.tsv')

        with io.open(filename, 'r', encoding='cp1252') as textfile:
            next(textfile)

            for line in textfile:
                tokens = line.strip().split('\t')
                __DEFAULT_STRUCTURE_IDS.append(int(tokens[1]))

    return __DEFAULT_STRUCTURE_IDS