Python 3 类型注解（Type Hints）与静态检查利器应用

一、现代 Python 类型示范

from typing import Optional, List, Dict

def fetch_user_posts(user_id: int, limit: int = 10) -> Optional[List[Dict[str, str]]]:
    if user_id <= 0:
        return None
    return [{"title": "示例笔记", "slug": "sample"}]