如何对具有可选参数的装饰器进行类型注释？

from typing import Optional, Callable

def my_decorator(optional_param: Optional[str]=None) -> Callable:
    def decorator(func: Callable) -> Callable:
        def wrapper(*args, **kwargs):
            # 装饰器逻辑
            if optional_param is not None:
                print("Optional parameter:", optional_param)
            result = func(*args, **kwargs)
            return result
        return wrapper
    return decorator

@my_decorator(optional_param="example")
def my_function() -> None:
    print("Hello, world!")