Platform based conditional compiling comes in two forms in Go, one is with file suffixes and the other is with build tags.
// +build", a single platform or a list can follow
Caveats for build tags:
// +buildconstraint must be placed at the top of the file, even before package clause.
|List of valid platforms for both build tags and file suffixes|
$GOOS list in https://golang.org/doc/install/source#environment for the most up-to-date platform list.