code: def data(self, value):
          
          if not value:
              value = b''
          if len(value) > self.SIZE:
              raise ValueError("The maximum tag size is {0}".format(self.SIZE))
          self._data = value
          while len(self._data) < self.SIZE:
              self._data += b'\x00'
docs: Set the byte data and fill up the bytes to fit the size.