public function push(AbstractModel $model)
    {
        $this->validateAdd($model);
        if (true === $this->willAdd($model)) {
            return $this;
        }
        if (true === $this->willRemove($model)) {
            $this->evict('removed', $model);
            $this->set('models', $model);
            return $this;
        }
        if (true === $this->hasOriginal($model)) {
            return $this;
        }
        $this->set('added', $model);
        $this->set('models', $model);
        return $this;
    }