code: func IsTerminal(file *os.File) bool {
  	var tios syscall.Termios
  	_, _, ep := syscall.Syscall(syscall.SYS_IOCTL,
  		uintptr(file.Fd()), syscall.TCGETS, uintptr(unsafe.Pointer(&tios)))
  	if ep != 0 {
  		// syscall failed, it's not a terminal
  		return false
  	}
  	return true
  }
docs: // May move to util/file? For now is here because it's the only
  // one used by colors.