async function soasync() {return 1;}

function* sogen()
{
  var v: number | undefined = undefined;
  let response = soasync();
  // const callback = yield;
  response.then((x)=>v=x);
  // examples of other things you can do
  setTimeout(yield, 2000);
  return v;
}

(function(){
const gen = sogen();
console.log(`${gen.next(gen.next).value}`);
// .next().next().value
}())