Sign the generated transaction envelope using a Hash(x) signature.

        :param preimage: The value to be hashed and used as a signer on the
            transaction envelope.
        :type preimage: str, bytes

def sign_preimage(self, preimage):
        """Sign the generated transaction envelope using a Hash(x) signature.

        :param preimage: The value to be hashed and used as a signer on the
            transaction envelope.
        :type preimage: str, bytes

        """
        if self.te is None:
            self.gen_te()
        self.te.sign_hashX(preimage)