flake8-future-annotations

Verifies python 3.7+ files use from __future__ import annotations if a type is used in the module that can be rewritten using PEP 563.

Pairs well with pyupgrade with the --py37-plus flag or higher, since pyupgrade only replaces type annotations with the PEP 563 rules if from __future__ import annotations is present.

For example:

from typing import List

def main() -> None:
    a_list: List[str] = []
    a_list.append("hello")

could be rewritten as:

from __future__ import annotations

def main() -> None:
    a_list: list[str] = []
    a_list.append("hello")