Hi, PEP 558 seems to be dormant, if not abandoned. There are at least two open issues for bugs resulting from the currently weird and inefficient behavior of `f_locals` and `locals()`. See https://bugs.python.org/issue30744 for an example of undesirable behaviour. PEP 588, or something like it, would fix those. I'd be happy to take over the PEP, or write a new one. I like PEP 588, although I would propose a simplification. The PEP mentions "tracing mode" and changes behavior according to whether a program is in "tracing mode" or not. I'd like to remove this distinction. Cheers, Mark.