请教一下如何实现函数的重载

interface User { 
  name: string; 
  age: number; 
} 
 
let user : User = {name : '1233', age : 222}; 
 
class SomeClass { 
 
  public test(para: User): number; 
 
  public test(para: number, flag: boolean): number; 
 
  public test(para: User | number, flag?: boolean): number { 
    // 具体实现 
    return 11; 
  } 
} 
 
const someClass = new SomeClass(); 
 
 
// ok 
someClass.test(user); 
someClass.test(123, false); 
 
// Error 
someClass.test(123); 
someClass.test(user, false);