[isoprophlex]

those nested if - for - for - if loops are horrendously difficult to understand.

take the fn starting at line 387. they comment why they do certain imports, but this function is comparatively underdocumented. it's not easy to wrap my head around the control flow. some bits are nested about 6 levels too deep for comfort, there are too many positions from which it can return or raise, and the function is about 3x too long

really difficult to grok what is happening here.