* nextID(max){
           var n=0; 
           while(n<max){
               yield n;
               n++; 
           }
           return
      }

 var f= this.nextID(5);
       console.log(f.next());

  var f= this.nextID(5);
       for(var x of f){
           console.log(x);
       }

function timeout(ms) {
   return new Promise((resolve) => {
    setTimeout(resolve, ms);
  });
}

async function asyncPrint(value, ms) {
  await timeout(ms);
  console.log(value)
}

asyncPrint('hello world', 2000);