title: What does this code do?
body: <pre><code>if (in_array($form['#submit'], 'search_box_form_submit')) {
      $key = array_search('search_box_form_submit', $form['#submit']);
      unset($form['#submit'][$key]);
  }
  
  array_unshift($form['#submit'], 'mymodule_search_box_submit');
  </code></pre>
  
  <p>What does the code do? I don't follow it well; I expect someone can explain it to me, line by line.</p>