Multiple dispatch via type annotations

overload.py

def overload(fn, overloads={}, nope=object()):
    def wrapper(*args, **kwargs):
        for sig, func in overloads.get(fn.__qualname__, []):
            try:
                bound = sig.bind(*args, **kwargs)
            except TypeError:
                continue
            for name, value in bound.arguments.items():
                if not isinstance(value, func.__annotations__[name]):
                    break
            else:
                return func(*args, **kwargs)
        raise TypeError("beep boop")
    overloads.setdefault(fn.__qualname__, []).append((inspect.signature(fn), fn))
    return wrapper