GetOptionKit\Argument::isEmpty PHP Метод

    public function isEmpty()
    {
        return $this->arg === null || empty($this->arg) && '0' !== $this->arg;
    }

 function testZeroValue()
 {
     $arg = new Argument('0');
     not_ok($arg->isShortOption());
     not_ok($arg->isLongOption());
     not_ok($arg->isEmpty());
 }