参考 https://blog.csdn.net/benben_2015/article/details/82227338
    1、初始化一个模块

    1. go mod init wserver

    2、自动更新依赖关系 (会生成go.sum 并更新go.mod)

    1. nidazhongdeMacBook-Pro:wserver nidazhong$ go mod tidy
    2. go: finding github.com/deckarep/golang-set v1.7.1
    3. go: downloading github.com/deckarep/golang-set v1.7.1