def loads(self, s, salt=None, return_header=False):
        """Reverse of :meth:`dumps`. If requested via `return_header` it will
        return a tuple of payload and header.
        """
        payload, header = self.load_payload(
            self.make_signer(salt, self.algorithm).unsign(want_bytes(s)),
            return_header=True)
        if header.get('alg') != self.algorithm_name:
            raise BadHeader('Algorithm mismatch', header=header,
                            payload=payload)
        if return_header:
            return payload, header
        return payload
Reverse of :meth:`dumps`. If requested via `return_header` it will
        return a tuple of payload and header.