function wait.for ( asyncFn, params ) {

    //call the async fn, returns immediately
    asyncFn(params, function(err,data){
               //here the data is ready
               thisFiber.err = err;
               thisFiber.data = data;
               thisFiber.resume(); //resume execution (after yield())
    });

    //we're in a fiber, so we can yield() to node's event loop 
    thisFiber.yield(); //pause here, give back control to node's event loop
    
    // the next line will be executed when thisFiber.resume() is called
    if (thisFiber.err) throw thisFiber.err; // throw into the caller of wait.for
    return thisFiber.data; //ok
  }