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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _is_compact_jws(self, jws):
 """ Check if we've got a compact signed JWT :param jws: The message :return: True/False """

        try:
            jwt = JWSig().unpack(jws)
        except Exception as err:
            logger.warning('Could not parse JWS: {}'.format(err))
            return False

        if "alg" not in jwt.headers:
            return False

        if jwt.headers["alg"] is None:
            jwt.headers["alg"] = "none"

        if jwt.headers["alg"] not in SIGNER_ALGS:
            logger.debug("UnknownSignerAlg: %s" % jwt.headers["alg"])
            return False

        self.jwt = jwt
        return True