Mypy is a separate program, running outside Python, typically as part of ... {x} * {y} = {x*y}" return bar b = foo(10) print(b(2)) Sure enough, this passes Mypy's checks. The function foo returns ...

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 ...