missing-return-type-private-function (ANN202)

Derived from the flake8-annotations linter.

Fix is sometimes available.

What it does

Checks that private functions and methods have return type annotations.

Why is this bad?

Type annotations are a good way to document the return types of functions. They also help catch bugs, when used alongside a type checker, by ensuring that the types of any returned values, and the types expected by callers, match expectation.

Example

def _add(a, b):
    return a + b

Use instead:

def _add(a: int, b: int) -> int:
    return a + b