I was struggling with the way the operators are written:

  clickStream.map(f).scan(g);

Then I realised that map() and scan() are not doing much when that line of code is executed. They only add a new operation step to a list of operations for clickStream. Only when an event is received, the saved list of operations gets executed. So, I think a better naming would have been addMap() and addScan(), because they only add operators. They don't map/scan anything when they are called.

I think the best tutorial for me would have been an article explaining what is going on under the hood. This tutorial does mention this implementation detail but only very briefly.

Anyway, without the tutorial, I wouldn't have realized this, so it was actually helpful. :)