vim-go tweaks for exercising the Go programming language

https://play.golang.org/p/1DFDNFXiJes is the problem and my solution. Can it be bettered?

My neovim configuration: https://github.com/kaihendry/dotfiles/blob/master/.vimrc

Inspired by https://medium.com/hackernoon/my-neovim-setup-for-go-7f7b6e805876 @sebdah ... https://www.youtube.com/watch?v=hHGivMVQXwY