title: Can I 'invert' a bool?
body: <p>I have some checks to see if a screen is active. The code looks like this:</p>
  
  <pre><code>if (GUI.Button(new Rect(Screen.width / 2 - 10, 50, 50, 30), "Rules")) //Creates a button
      {
          if (ruleScreenActive == true) //check if the screen is already active
              ruleScreenActive = false; //handle according to that
          else 
              ruleScreenActive = true;
      }
  </code></pre>
  
  <p>Is there any way to - whenever I click the button - invert the value of <code>ruleScreenActive</code>?</p>
  
  <p>(This is C# in Unity3D)</p>