public function blueprints()
    {
        if (!$this->blueprints){
            $this->blueprints = new Blueprint;
        } elseif (\is_callable($this->blueprints)) {
            // Lazy load blueprints.
            $blueprints = $this->blueprints;
            $this->blueprints = $blueprints();
        }
        return $this->blueprints;
    }