For example, you have an object `A`, you want to extend it and modify some prop; then create a new interface B:
export interface B extends Omitamp;amp;lt;A, 'x' | 'y'amp;amp;gt; {
x: string; ...……
// 类型别名
type ISum = (x: number, y: number) =amp;amp;gt; number
// 应用如下:
let sum: ISum = (a, b) =amp;amp;gt; a + b
console.log(sum(3, 2));
//函数重载
function fn(name: string): string;
fu ...……