I agree, it's straightforward. I just thought it could be useful to have a proper definition in the official documentation.

For example, this question on StackOverflow actually received many views: https://stackoverflow.com/questions/111234/what-is-a-callable

What do you think is the best documentation entry I can link to while mentioning a "callable" type? Just the builtin "callable()"? The `collections.abc.Callable` is interesting but does not look very appropriate for basic functions.