# File lib/aws/simple_workflow/decision_task.rb, line 304
      def request_cancel_activity_task activity_or_activity_id

        id = activity_or_activity_id.is_a?(ActivityTask) ?
          activity_or_activity_id.activity_id :
          activity_or_activity_id

        add_decision :request_cancel_activity_task, { :activity_id => id }

      end