code: def set_tag(self, tag):
          '''
          Sets the tag.
          If the Entity belongs to the world it will check for tag conflicts.
          '''
          if self._world:
              if self._world.get_entity_by_tag(tag):
                  raise NonUniqueTagError(tag)
          self._tag = taf set_tag(self, tag):
          '''
          Sets the tag.
          If the Entity belongs to the world it will check for tag conflicts.
          '''
          if self._world:
              if self._world.get_entity_by_tag(tag):
                  raise NonUniqueTagError(tag)
          self._tag = tag
docs: Sets the tag.
          If the Entity belongs to the world it will check for tag conflicts.