code: def sign(self, data: bytes, v: int = 27) -> Signature:
          
          assert v in (0, 27), 'Raiden is only signing messages with v in (0, 27)'
          _hash = eth_sign_sha3(data)
          signature = self.private_key.sign_msg_hash(message_hash=_hash)
          sig_bytes = signature.to_bytes()
          # adjust last byte to v
          return sig_bytes[:-1] + bytes([sig_bytes[-1] + v])
docs: Sign data hash with local private key