code: func findExe(cmd string, paths []string) (string, bool) {
  	for _, p := range paths {
  		cp := filepath.Join(p, cmd)
  		if c, err := exec.LookPath(cp); err == nil {
  			return c, true
  		}
  	}
  	return cmd, false
  }
docs: // findExe looks for an executable command on a set of paths.
  // If it cannot find it, returns cmd.