mySetInterval

写一个 mySetInterval(fn, a, b),每次间隔 a,a+b,a+2b 的时间，然后写一个 myClear，停止上面的 mySetInterval

function mySetInterval(fn,a,b,flag = 0){
    setTimeout(() => {
        fn(a + b * flag)
        flag++
        mySetInterval && mySetInterval(fn,a,b,flag)
    },a + b * flag)
}

function myClearInterval(){
    window.mySetInterval && (window.mySetInterval = null)
}

function log(timeInterval){
    console.log(timeInterval)
}