def sign_bitcoin(self, message, compressed=False):
        """ Signs a message using the underlying non-extended private
        key such that it is compatible with bitcoind, bx, and other
        Bitcoin clients/nodes/utilities.

        Note:
            0x18 + b\"Bitcoin Signed Message:" + newline + len(message) is
            prepended to the message before signing.

        Args:
            message (bytes or str): Message to be signed.
            compressed (bool):
                True if the corresponding public key will be
                used in compressed format. False if the uncompressed version
                is used.

        Returns:
            bytes: A Base64-encoded byte string of the signed message.
            The first byte of the encoded message contains information
            about how to recover the public key. In bitcoind parlance,
            this is the magic number containing the recovery ID and
            whether or not the key was compressed or not. (This function
            always processes full, uncompressed public-keys, so the
            magic number will always be either 27 or 28).
        """

        return self._key.sign_bitcoin(message, compressed)
Signs a message using the underlying non-extended private
        key such that it is compatible with bitcoind, bx, and other
        Bitcoin clients/nodes/utilities.

        Note:
            0x18 + b\"Bitcoin Signed Message:" + newline + len(message) is
            prepended to the message before signing.

        Args:
            message (bytes or str): Message to be signed.
            compressed (bool):
                True if the corresponding public key will be
                used in compressed format. False if the uncompressed version
                is used.

        Returns:
            bytes: A Base64-encoded byte string of the signed message.
            The first byte of the encoded message contains information
            about how to recover the public key. In bitcoind parlance,
            this is the magic number containing the recovery ID and
            whether or not the key was compressed or not. (This function
            always processes full, uncompressed public-keys, so the
            magic number will always be either 27 or 28).