https://developer-community.sage.com/topic/12031-%F0%9D%93%92%F0%9D%93%AA%F0%9D%93%B5%F0%9D%93%B5~%F0%9D%93%A3%F0%9D%93%B8~%F0%9D%93%AD%F0%9D%93%AE%F0%9D%93%B5%F0%9D%93%BD%F0%9D%93%AA%E2%84%A2how-late-can-you-cancel-a-refundable-delta-flight/
https://developer-community.sage.com/topic/12039-call~to~deltahow-late-can-you-cancel-a-refundable-delta-flight/