play-with-go.dev - i need help

play-with-go.dev

https://play-with-go.dev/

An introduction to play-with-go.dev guides

Get started with Go

Go Modulesチュートリアル(Go fundamentals)

Working with private modules

How to use and tweak Staticcheck

Developer tools as module dependencies

New features in Go 1.16

Installing Go programs directly

Retract Module Versions