docs: def execute(self):
          """
          Executes the query if self.query_set_obj is set
          :return: The result of aggregation query
          """
          if self.query_set_obj is None:
              return []
  
          if self.is_mongoengine:
              result = self.query_set_obj.aggregate(*self.get_query())
          else:
              result = self.query_set_obj.aggregate(self.get_query())
  
          if IS_PYMONGO_3:
              result = list(result)
          else:
              result = result.get('result')
          if result:
              return result
          return []