Ouzo\Utilities\Functions::not PHP Method

    public static function not($predicate)
    {
        return function ($object) use($predicate) {
            return !$predicate($object);
        };
    }

 /**
  * @test
  */
 public function shouldNegatePredicate()
 {
     $this->assertFalse(Functions::call(Functions::not(Functions::identity()), true));
     $this->assertTrue(Functions::call(Functions::not(Functions::identity()), false));
 }