util._extend(target, source)
稳定性： 0 - 弃用：请改用
Object.assign()。util._extend() 方法从未打算在 Node.js 的内部模块之外使用。但社区还是找到了并使用了它。
🌐 The util._extend() method was never intended to be used outside of internal
Node.js modules. The community found and used it anyway.
它已被弃用，不应在新代码中使用。JavaScript 通过 Object.assign() 提供了非常类似的内置功能。
🌐 It is deprecated and should not be used in new code. JavaScript comes with very
similar built-in functionality through Object.assign().