# Tweet by [@keefmoon](http://twitter.com/keefmoon) on 2017-11-04 20:24:21 > [!INFO] Archived from [original tweet](http://twitter.com/keefmoon/status/926907994008408066) In reply to: [@nicklockwood](http://twitter.com/nicklockwood/status/926848056238198784) @nicklockwood @SteveStreza There’s lots of time you might want to provide data that shouldn’t be mutated, using struct let. The response from an API call for example.