public function add($constant)
    {
        if (!$constant instanceof ConstantInterface) {
            throw new \InvalidArgumentException(
                'This Constant must be a instance of \ClassGeneration\ConstantInterface'
            );
        }

        if ($constant->getName() === null) {
            $constant->setName('constant' . ($this->count() + 1));
        }

        return parent::add($constant);
    }