I am trying to install a proof-of-work proxy server from the link: https://docs.iota.org/docs/node-software/0.1/iri/how-to-guides/install-a-pow-proxy on Raspberry Pi 3B. However, when I try to build an executable file at step 4, I get the following error:
main.go:22:8: cannot find package "github.com/mholt/caddy/caddy/caddymain" in any of:
/usr/lib/go/src/pkg/github.com/mholt/caddy/caddy/caddymain (from $GOROOT )
/home/pi/go/src/github.com/mholt/caddy/caddy/caddymain (from $GOPATH)