title: async task sending result to gui
body: <p>Can an async task send <strong>periodically</strong> a result to the GUI?</p>
  
  <p>For example: I have 3 things I'd like my async task to do. After each thing, I'd like
  to send a string back to the gui: <code>"task x completed"</code></p>
  
  <p>Can I do this without creating 3 async tasks?</p>