code: def data_size(self):
          
          # Container
          if is_container(self._data):
              byte_length, bit_length = self._data.container_size()
              return byte_length + math.ceil(bit_length / 8)
          # Field
          elif is_field(self._data):
              return math.ceil(self._data.bit_size / 8)
          else:
              return 0
docs: Returns the size of the :attr:`data` object in bytes (read-only).