title: AS3 deletion of unused variables
body: <p>How can you delete unused and uninitialized variables? I have some masks and filters that may get used depending on screen size, but when I don't need them, can I simply get rid of them? For example:</p>
  
  <pre><code>var appMask:Shape;
  if ((screenR % 1) &gt; 0) {
      appMask = new Shape;
      appMask.graphics.beginFill(0x000000);
      appMask.graphics.drawRect(0,0,screenW,screenH);
      appMask.graphics.endfill();
  } else {
      //delete appMask variable?
  }
  </code></pre>
  
  <p>I have also considered making the new Shape on variable creation as well and setting it to null for garbage cleanup later, but I want to ensure this will work as expected.</p>
  
  <p>Thanks!</p>