code: func OSVersion() (osVersion string, err error) {
  	var un syscall.Utsname
  	err = syscall.Uname(&un)
  	if err != nil {
  		return
  	}
  	charsToString := func(ca []int8) string {
  		s := make([]byte, len(ca))
  		var lens int
  		for ; lens < len(ca); lens++ {
  			if ca[lens] == 0 {
  				break
  			}
  			s[lens] = uint8(ca[lens])
  		}
  		return string(s[0:lens])
  	}
  	osVersion = charsToString(un.Sysname[:]) + " " + charsToString(un.Release[:]) + "." + charsToString(un.Machine[:])
  	return
  }
docs: // OSVersion returns version info of operation system.
  // e.g. Linux 4.15.0-45-generic.x86_64