title: Value as the key
body: <p>I have an array like this:</p>
  
  <pre><code>$options[0] = 1;
  $options[1] = 2;
  $options[2] = 3;
  $options[3] = 'something';
  </code></pre>
  
  <p>How can I have the value of each array element put as the key, so the array looks like this:</p>
  
  <pre><code>$options[1] = 1;
  $options[2] = 2;
  $options[3] = 3;
  $options['something'] = 'something';
  </code></pre>
  
  <p>Is there a built in function for this?</p>