Clarification: I have a tendency to mention constructs from other threads in a discussion. This might suggest that I'm propose using this not-yet-included or even accepted feature as a solution. For instance Guido's reaction to my last message might be an indicator of misinterpreting this, although I'm not sure if I was Prinarily addressed at all (despite that the to/cc suggested it). Anyway, I just want to make sure: If I'm mentioning stackless or codef or greenlet, this does not imply that I propose to code the solution to async by implementing such a thing, first. The opposite is true. I mean such meantioning more like a macro-like feature: I'm implementing structures using the existing things, but adhere to a coding style that stays compatible to one of the mentioned principles. This is like a macro feature of my brain - I talk about codef, but code it using yield-from. So please don't take me wrong that I want to push for features to be included. This is only virtual. I use yield constructs, but obey the codef protocol, for instance. And as an addition: when I'm talking of generators implemented by yield from, then this is just a generator that can yield from any of its sub-functions. I am not talking about tasks or schedulars. These constructs do not belong there. I'm strongly against using "yield from" for this. It is a building block for generatos resp. coroutines, and there it stops ! Higher level stuff should by no means use those primitives at all. Sent from my Ei4Steve