When instrumenting regular for loops, we instrument the FOR_ITER instruction as the LEFT branch and the POP_ITER instruction as the RIGHT branch.

This doesn't work for async for as it uses exceptions to exit the loop.
Raising an exception is the documented behavior for exiting a [async] generator, so we will still need to generate an event for the exception being raised, much as we do in INSTRUMENTED_END_FOR as well as the BRANCH events.

Linked PRs

• GH-128534: Instrument branches for async for loops. #130569
• GH-128534: Fix behavior of branch monitoring for async for #130847