code: def get_att(self, parameter, as_reference=True):
          
          if as_reference:
              return troposphere.GetAtt(
                  self.__custom_stack_obj,
                  troposphere.Ref(parameter)
              )
          else:
              return troposphere.GetAtt(
                  self.__custom_stack_obj,
                  parameter
              )
docs: Retrieves an attribute from an existing stack
          :param parameter: The output parameter which should be retrieved
          :param as_reference: Is the parameter a reference (Default) or a string
          :return: Value of parameter to retrieve