Go fix cannot find package issue

2 description

When I do the Exercise: Slices on a tour of Go

The following issue comes:

➜ moretypes git:(next) go build exercise-slices.go
exercise-slices.go:3:8: cannot find package "golang.org/x/tour/pic" in any of:
/usr/local/go/src/golang.org/x/tour/pic (from $GOROOT)
/home/workspace/go/src/golang.org/x/tour/pic (from $GOPATH)

3 fix steps

3.1 go get the package

$ go get golang.org/x/tour/pic

But the following issue comes again:

➜ moretypes git:(next) go get golang.org/x/tour/pic
package golang.org/x/tour/pic: unrecognized import path "golang.org/x/tour/pic"
(https fetch: Get https://golang.org/x/tour/pic?go-get=1: dial tcp
[2a00:1450:400e:800::200e]:443: connect: network is unreachable)

The reason is that `golang.org` cann't be accessed from China mainland.

3.1.1 activate proxy

Activate the proxy at shell help to go get

export {http,https,ftp}_proxy=''

Note: make sure you have the proxy first.