text: <?php
  namespace Kahlan\Matcher;
  
  class ToBeNull extends ToBe
  {
      /**
       * Expect that `$actual` is `null`.
       *
       * @param  mixed $actual The actual value.
       * @param null $expected The expected vale
       *
       * @return bool
       */
      public static function match($actual, $expected = null)
      {
          return parent::match($actual, null);
      }
  
      /**
       * Returns the description message.
       *
       * @return string The description message.
       */
      public static function description()
      {
          return "be null.";
      }
  }
  