code: func envOverride(target *string, platform Platform, key string) {
  	key = strings.ToUpper(fmt.Sprintf(
  		"GOX_%s_%s_%s", platform.OS, platform.Arch, key))
  	if v := os.Getenv(key); v != "" {
  		*target = v
  	}
  }
docs: // envOverride overrides the given target based on if there is a
  // env var in the format of GOX_{OS}_{ARCH}_{KEY}.