如何创建返回修改后的泛型类型实例的泛型函数？

function modifyGenericInstance<T>(instance: T): T {
  // 在这里对泛型实例进行修改
  return instance;
}

class Person {
  constructor(public name: string, public age: number) {}
}

function modifyGenericInstance<T>(instance: T): T {
  if (instance instanceof Person) {
    // 修改 Person 类型实例的属性
    instance.name = "John Doe";
    instance.age = 30;
  }
  return instance;
}

const person = new Person("Jane Smith", 25);
const modifiedPerson = modifyGenericInstance(person);
console.log(modifiedPerson); // 输出: Person { name: 'John Doe', age: 30 }