title: array_merge & array_unique
body: <p>Is there an array function in PHP that somehow does array_merge, comparing the <strong>values</strong>, ignoring the keys? I think that <code>array_unique(array_merge($a, $b))</code> works, however I believe there must be a nicer way to do this.</p>
  
  <p>eg.</p>
  
  <pre><code>$a = array(0 =&gt; 0, 1 =&gt; 1, 2 =&gt; 2);
  $b = array(0 =&gt; 2, 1 =&gt; 3, 2 =&gt; 4);
  </code></pre>
  
  <p>resulting in: </p>
  
  <pre><code>$ab = array(0 =&gt; 0, 1 =&gt; 1, 2 =&gt; 2, 3 =&gt; 3, 4 =&gt; 4);
  </code></pre>
  
  <p>Please note that I don't care about the keys in <code>$ab</code>, however it <em>would be nice</em> if they were ascending, starting at 0 to <code>count($ab)-1</code>.</p>