Usage:
go get [-d] [-t] [-u] [-v] [-insecure] [build flags] [packages]
Note that package patterns are allowed and are expanded after resolving the module versions. For example, ‘go get golang.org/x/perf/cmd/…’ adds the latest golang.org/x/perf and then installs the commands in that latest version.
可以用…扩展，表示当前目录下的所有package
features
-d: 下载源码和依赖，但是不要build或者install
-t：下载测试依赖。一般下载依赖的时候是不必考虑_test.go中的依赖的
-u：在满足版本语义的前提下更新依赖
When the -t and -u flags are used together, get will update test dependencies as well.
-insecure： flag permits fetching from repositories and resolving custom domains using insecure schemes such as HTTP.
