code: def create_entity(self):
          
          self._highest_id_seen += 1
          entity = Entity(self._highest_id_seen, self)
          self._entities.append(entity)
          return entity
docs: Create a new entity.
  
          The entity will have a higher UID than any previously associated
          with this world.
  
          :return: the new entity
          :rtype: :class:`essence.Entity`