'Parse this from a header value'

@classmethod
def parse(cls, value, strong=True):

    if (value == '*'):
        return AnyETag
    if (not value):
        return cls([])
    matches = _rx_etag.findall(value)
    if (not matches):
        return cls([value])
    elif strong:
        return cls([t for (w, t) in matches if (not w)])
    else:
        return cls([t for (w, t) in matches])
