docs: def _len_objid(self):
      '''Get the actual size of the content, as some attributes have variable sizes'''
      try:
          return self._size
      except AttributeError:
          temp = (self.object_id, self.birth_vol_id, self.birth_object_id, self.birth_domain_id)
          self._size = sum([ObjectID._UUID_SIZE for data in temp if data is not None])
          return self._size