Why couldn't Python do something like: >>> _tmp = getitem(t, 0) >>> setitem(t, 0, _tmp) >>> try: >>> _tmp2 = _tmp.__iadd__([2]) >>> exc

Why couldn't Python do something like: >>> _tmp = getitem(t, 0) >>> setitem(t, 0, _tmp) >>> try: >>> _tmp2 = _tmp.__iadd__([2]) >>> except AttributeError: >>> _tmp2 = _tmp.__add__([2]) >>> setitem(t, 0, _tmp2) Then if the first setitem raises, the rest of the code will be skipped. Obviously this isn't perfect: 1. If setitem has strange side-effects, this will cause them to happen twice. 2. If setitem raises based on the value (rather than the key), this won't notice that. But otherwise, it seems like a pretty straightforward improvement, no?