[michalc]

Indirectly: the initial version was a single function, so could have been used in a decorator easily enough.

The issue is what happens on exceptions to avoid tasks hanging around forever. Exceptions propagate “forward” in the pipeline fairly automatically. However, getting the ones “behind” the exception to notice: that was tricky. The best I came up with was the bit of state wrapped up in buffered_pipeline that notices the exceptions and cancels the tasks.