Decorator with an optional parameter

decorator.py

"""Decorator with an optional parameter."""

from collections.abc import Callable
import functools
from typing import Optional

FUNCS = {}


def register(func: Optional[Callable] = None,
             name: Optional[str] = None) -> Callable:
    if func is None:
        return functools.partial(register, name=name)

    if name is None:
        name = func.__name__
    FUNCS[name] = func
    return func


@register
def spam():
    pass


@register(name='eggs')
def _eggs():
    pass


assert FUNCS == {'spam': spam, 'eggs': _eggs}