title: What is the purpose of "do!" notation in F#?
body: <p>I'm a beginner in F#, so it's a simple question and maybe a duplicate, but I couldn't find the answer anywhere...</p>
  
  <p>I'm reading <a href="http://lorgonblog.spaces.live.com/Blog/cns!701679AD17B6D310!1886.entry" rel="noreferrer">this LOGO DSL implementation</a> and I don't understand, what is the meaning of the "do!" notation in here:</p>
  
  <pre><code>    this.Loaded.Add (fun _ -&gt;
          async {
              do! Async.Sleep 200
              for cmd in theDrawing do
                  do! this.Execute(cmd)
          } |&gt; Async.StartImmediate 
      )
  </code></pre>
  
  <p>Can you help?</p>