What does `contextlib.contextmanager` allow and how does `yield` work inside it?

Question

Python Developer — Hard

What does `contextlib.contextmanager` allow and how does `yield` work inside it?

Accepted Answer

`contextlib.contextmanager` allows writing a context manager using a generator function. Code before yield runs in __enter__, the yielded value is the target, and code after yield runs in __exit__. Exceptions from the with block are thrown into the generator at the yield point.