from collections.abc import Callable, Mapping from typing import TypeAlias, TypeVar # Apparently you need Python 3.13 for type var defaults to work. But since this # is just a stub file, it's okay if they aren't supported at runtime. KIn = TypeVar("KIn") KOut = TypeVar("KOut", default=KIn) VIn = TypeVar("VIn") VOut = TypeVar("VOut", default=VIn) Path: TypeAlias = tuple[KIn, ...] # remap() is Complicated and really difficult to define a type for, so I'm not # surprised the boltons package doesn't try to type it for you. This particular # type declaration works fine for my use of the function, but it's actually # vastly more flexible than that - it'll accept any iterable as the root, not # just mappings, and you can provide "enter" and "exit" callables to support # arbitrary data structures. def remap( root: Mapping[KIn, VIn], visit: Callable[[Path[KIn], KIn, VIn], tuple[KOut, VOut] | bool], reraise_visit: bool = False, ) -> Mapping[KOut, VOut]: ...