tializer is called
    with a string that doesn't match *regex*.

    :param str regex: a regex string to match against
    :param int flags: flags that will be passed to the underlying re function
        (default 0)
    :param callable func: which underlying `re` function to call (options
        are `re.fullmatch`, `re.search`, `re.match`, default
        is ``None`` which means either `re.fullmatch` or an emulation of
        it on Python 2). For performance reasons, they won't be used directly
        but on a pre-`re.compile`\ ed pattern.

    .. versionadded:: 19.2.0
    Ú	fullmatchNz