title: Unset inside array_walk_recursive not working
body: <pre><code>  array_walk_recursive($arr, function(&amp;$val, $key){
      if($val == 'smth'){
        unset($val);          // &lt;- not working, unset($key) doesn't either
        $var = null;          // &lt;- setting it to null works
      }
    });
  
    print_r($arr);
  </code></pre>
  
  <p>I don't want it to be null, I want the element out of the array completely. Is this even possible with array_walk_recursive?</p>