title: Underscore Arrow (_ => ...) What Is This?
body: <p>Reading through C# in a Nutshell I noticed this bit of code that I've never came across:</p>
  
  <pre><code>_uiSyncContent.Post(_ =&gt; txtMessage.Text += "Test");
  </code></pre>
  
  <p>What is that underscore followed by an arrow? I've seen Lambda expressions written in a similar way but nothing with an underscore.</p>