code: def register(self, model, values=None, instance_values=None):
          
  
          if model in self._models:
              raise Exception("%s is already registered" % model)
  
          self._models[model] = CacheConfig(values, instance_values)
docs: Registers a model with this group.
  
          :param values: A list of values that should be incremented \
          whenever invalidate_cache is called for a instance or class \
          of this type.
  
          :param instance_values: A list of attribute names that will \
          be looked up on the instance of this model that is passed to \
          invalidate_cache. The value resulting from that lookup \
          will then be incremented.