def python_format(catalog, message):
    if 'python-format' not in message.flags:
        return
    msgids = message.id
    if not isinstance(msgids, (list, tuple)):
        msgids = (msgids,)
    msgstrs = message.string
    if not isinstance(msgstrs, (list, tuple)):
        msgstrs = (msgstrs,)

    for msgid, msgstr in izip(msgids, msgstrs):
        if msgstr:
            _validate_format(msgid, msgstr)
Verify the format string placeholders in the translation.
dataset/ETHPy150Open IanLewis/kay/kay/lib/babel/messages/checkers.py/python_format