I'm aware that using Firebase REST we could POST and have a Firebase unique id generated. For example, a id that looks like this, -Kbz13Uo3. 1. How do we do this using AngularFire2? 2. Or maybe should we be asking is there a need to use Firebase Unique Id in the first place? 3. What is a good self generated unique id when using it with Firebase? GUID?