code: func Isatty(fd uintptr) bool {
  	var termios syscall.Termios
  
  	_, _, err := syscall.Syscall6(syscall.SYS_IOCTL, fd,
  		uintptr(syscallGetTermios), uintptr(unsafe.Pointer(&termios)), 0, 0, 0)
  
  	return err == 0
  }
docs: // isatty checks whether FD is a tty. Doesn't work on Windows.