Libraries such as Curio and asyncio provide a debugging facility that allows someone to view the call stack of generators/coroutines.  For example, the _task_get_stack() function in asyncio/base_tasks.py.  This works by manually walking up the chain of coroutines (by following cr_frame and gi_frame links as appropriate).   

The only problem is that it doesn't work if control flow falls into an async generator because an "async_generator_asend" instance is encountered and there is no meaningful way to proceed any further with stack inspection.

This problem could be fixed if "async_generator_asend" and "async_generator_athrow" instances exposed the underlying "ags_gen" and "agt_gen" attribute that's held inside the corresponding C structures in Objects/genobject.c.  

Note: I made a quick and dirty "hack" to Python to extract "ags_gen" and verified that having this information would allow me to get complete stack traces in Curio.