Null.php

1. 9.x drupal/core/modules/views/lib/Drupal/views/Plugin/views/argument/Null.php
2. 9.x drupal/core/vendor/twig/twig/lib/Twig/Node/Expression/Test/Null.php

<?php

/*
 * This file is part of Twig.
 *
 * (c) 2011 Fabien Potencier
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

/**
 * Checks that a variable is null.
 *
 * <pre>
 *  {{ var is none }}
 * </pre>
 *
 * @package twig
 * @author  Fabien Potencier <fabien@symfony.com>
 */
class Twig_Node_Expression_Test_Null extends Twig_Node_Expression_Test {
  public function compile(Twig_Compiler $compiler) {
    $compiler
      ->raw('(null === ')
      ->subcompile($this
      ->getNode('node'))
      ->raw(')');
  }

}