code: def on_success(handler, using=None):
      
  
      connection = get_connection(using)
      if getattr(connection, 'transaction_signals_context_list', False):
          connection.transaction_signals_context_list[-1].register(handler)
      else:
          if settings.DEBUG:
              logger.warning(
                  'For on success signal should be activated transaction signals via transaction_signals decorator.'
                  'Function is called immediately now.'
              )
          handler()
docs: Register a handler or a function to be called after successful code pass.
      If transaction signals are not active the handler/function is called immediately.
      :param handler: handler or function that will be called.
      :param using: name of the database