const hello : string = "Hello World!" interface User { Name?: string; Age: number; Print(): any; } class Member { Name: string; Age: number; constructor(name: string, age: number) { this.Name = name; this.Age = age; } Print() { console.log(`${hello} ${this.Name}! You are !${this.Age} years old!`); } } function PrintUser(u: User) { u.Print(); } PrintUser(new Member("Jason", 30));