title: Merge two flat indexed arrays of equal size so that values are pushed into the result in an alternating fashion
body: <p>Suppose I have two arrays:</p>
  <pre><code>$a1 = array(0, 1, 2);
  $a2 = array(3, 4, 5);
  </code></pre>
  <p>I want to be able to do a merge technique that alternates the array values and not just concatenate them. I want this result:</p>
  <pre><code>array(0, 3, 1, 4, 2, 5);
  </code></pre>
  <p>Is there a native way to do this as performance is an issue here since I need to do this thousands of times</p>
  <p>Please note, I know I can do it like this:</p>
  <pre><code>for (var $i = 0; $i &lt; count($a1); $i++) {
      newArray[] = $a1[$i];
      newArray[] = $b1[$i];
  }
  </code></pre>
  <p>I'm looking for a built in way if there is a faster one.</p>