What is the meaning of $form['cid']['#value']? /**
     * @Implement of hook_form_alter()
     */
    function mycaptcha_form_alter(&amp;$form, &amp;$form_state, $form_id) {
     if ($form_id == 'comment_form' &amp;&amp; !$form['cid']['#value']) {
。。。。。


Someone has written the above code, but I don't know what $form['cid']['#value'] is for, and what I should use in Drupal 7.
cid is the comment id. And this comment checks if it is empty or not. When it is not empty, it means that we are editing an existing comment as opposed to creating a new one and this code doesn't need to run.