docs: def binary(self):
          """
          return encoded representation
          """
          creation_size = len(self.creation)
          if creation_size == 1:
              return (
                  b_chr(_TAG_PORT_EXT) +
                  self.node.binary() + self.id + self.creation
              )
          elif creation_size == 4:
              return (
                  b_chr(_TAG_NEW_PORT_EXT) +
                  self.node.binary() + self.id + self.creation
              )
          else:
              raise OutputException('unknown port type')