threepointone

// this is a generic runner for iterators 
// for every yield, it checks to see if any time is remaining 
// on the idle loop, and executes more work if so. 
// else, it queues up for the next idle period 

function go(it, callback){
  requestIdleCallback(deadline => {
    let val = it.next()
    while(!val.done){
      if(deadline.timeRemaining() <= 0){