It's precisely all the help you need to go and look up your notes on coroutines from college. You did go to college didn't you? Or are you an anti-college hipster, suddenly finding the limitations of that approach.
Come on, I've got a reasonable point here. People post on forums asking these questions which should have been answered during their educations.
If civil engineers had a forum site and someone asked "how do I calculate the load a simple beam", people would say, what the fuck are you doing in your job if you don't know that? Who is employing you and why? Where did you go to college? Who was your tutor because next time I'm at a dinner at my college I'm going to ask him how the fuck did they pass you.
Our current trend of saying college doesn't matter really starts to be a problem when professional programmers (yeah I'm assuming that the guy in the question is) are asking basic questions like this. This shows that we do need college education for programmers.
It also irritates me - this guy could have taken the time to learn all these basics, but for whatever reason he thought it didn't matter, and now he's paying for it.
This is why you study CS at university before you start work as a programmer. Otherwise you end up being amazed by the basic CS concepts, or worse, you end up reinventing them badly.