from contextlib import contextmanager

@contextmanager
def custom_context(name):
    print(f"進入上下文: {name}")
    try:
        yield name  # 提供資源
    finally:
        print(f"退出上下文: {name}")

# 使用 with 語法
with custom_context("示範") as ctx:
    print(f"內部執行: {ctx}")