Literally convert Go code to Crystal code. I have not looked into Crystal enough to confirm it's features are a superset of Go's. For example, I saw that Kotlin w/ the advent of their coroutines, had most of Go's features so I wrote a transpiler[0] that got pretty far (can run all of this [0]). I abandoned the project because I have abandoned the JVM.
0 - https://github.com/cretz/go2k 1 - https://github.com/cretz/go2k/tree/master/compiler/src/test/...