code: def source_group_receiver(self, sender, source, signal, **kwargs):
          
  
          from imagekit.cachefiles import ImageCacheFile
          source_group = sender
  
          # Ignore signals from unregistered groups.
          if source_group not in self._source_groups:
              return
  
  
          #OVERRIDE HERE -- pass specs into generator object
          specs = [generator_registry.get(id, source=source, specs=spec_data_field_hash[id]) for id in
                  self._source_groups[source_group]]
          callback_name = self._signals[signal]
          #END OVERRIDE
  
          for spec in specs:
              file = ImageCacheFile(spec)
              call_strategy_method(file, callback_name)
docs: Relay source group signals to the appropriate spec strategy.