The one place they are pretty convenient is in languages (like Python) where multiple return values from one function can be used as multiple input parameters to another. But, the use-cases where ...

In order to store key-value pairs in Python, you can use the dictionary data structure. The dictionary functions in a similar fashion to the Python list, in that it is a collection of data.

including inner functions and Python's scoping rules. I do, however, want to ask the question "how can you use Mypy to check all of this?" from typing import Callable def foo(x: int) -> Callable: def ...