Promises
C# Promises:
https://zenfulcrum.com/docs/browser/Promises.html
Promises for Game Development:
https://www.gamasutra.com/blogs/AshDavis/20150629/247248/Promises_for_Game_Development.php
https://src-bin.com/en/q/2530a71
https://github.com/Real-Serious-Games/C-Sharp-Promise
https://www.what-could-possibly-go-wrong.com/promises-for-game-development/
https://en.wikipedia.org/wiki/Futures_and_promises
https://stackoverflow.com/questions/23844076/promises-with-unity
https://github.com/Real-Serious-Games/c-sharp-promise
https://github.com/Real-Serious-Games/c-sharp-promise#understanding-promises
https://github.com/nickgravelyn/UnityToolbag/tree/master/Future
http://stephenlautier.blogspot.com/p/upromise.html
https://blog.theknightsofunity.com/coroutines-in-unity-encapsulating-with-promises-part-2/