code: def DeregisterAttributeContainer(cls, attribute_container_class):
      
      container_type = attribute_container_class.CONTAINER_TYPE.lower()
      if container_type not in cls._attribute_container_classes:
        raise KeyError(
            'Attribute container class not set for container type: '
            '{0:s}.'.format(attribute_container_class.CONTAINER_TYPE))
  
      del cls._attribute_container_classes[container_type]
docs: Deregisters an attribute container class.
  
      The attribute container classes are identified based on their lower case
      container type.
  
      Args:
        attribute_container_class (type): attribute container class.
  
      Raises:
        KeyError: if attribute container class is not set for
                  the corresponding container type.