Slide 54 is vague

1. You just casually wrote flatMapWithIndex there without explaining what the thing does.
2. You should really explain the benefits of what you're doing with this code since you seem to be making me, the programmer, work more up front as opposed to just taking Alamofire's tried-and-tested approach.
3. The 'Rx' part seems to end at the flatMapWitIndex bit.