title: How to merge subarray values and remove duplicates?
body: <pre><code>$arr[] = array('A','B');
  $arr[] = array('C','B');
  ...
  </code></pre>
  
  <p>I need to get the merged result of all sub array of <code>$arr</code> .</p>
  
  <p>And for duplicated entries,should fetch only one.</p>