1.Laravel 中的 Pivot 表与多对多关系

https://9iphp.com/web/laravel/pivot-tables-and-many-to-many-relationships.html

2.Laravel 的 tap 函数用法

https://laravel-china.org/articles/3893/laravel-tap-usage

3.Laravel 5.5 模型关联

https://laravel-china.org/docs/laravel/5.5/eloquent-relationships/1333

4.Laravel Collection “tap” Method

https://laravel-news.com/collection-tap

5.goroutine同步方法总结

https://yq.aliyun.com/articles/649314

6.面向对象设计之里氏替换原则(LSP)

https://juejin.im/post/5a31ecedf265da43346fed08