def parse_accept_header(value, cls=None):
    """Parses an HTTP Accept-* header.  This does not implement a complete
    valid algorithm but one that supports at least value and quality
    extraction.

    Returns a new :class:`Accept` object (basically a list of ``(value, quality)``
    tuples sorted by the quality with some additional accessor methods).

    The second parameter can be a subclass of :class:`Accept` that is created
    with the parsed values and returned.

    :param value: the accept header string to be parsed.
    :param cls: the wrapper class for the return value (can be
                         :class:`Accept` or a subclass thereof)
    :return: an instance of `cls`.
    """
    if cls is None:
        cls = Accept

    if not value:
        return cls(None)

    result = []
    for match in _accept_re.finditer(value):
        quality = match.group(2)
        if not quality:
            quality = 1
        else:
            quality = max(min(float(quality), 1), 0)
        result.append((match.group(1), quality))
    return cls(result)
dataset/ETHPy150Open Eforcers/gae-flask-todo/lib/werkzeug/http.py/parse_accept_header/original