code: func MakeRaw(fd int) (*State, error) {
  	var oldState State
  	if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlReadTermios, uintptr(unsafe.Pointer(&oldState.termios)), 0, 0, 0); err != 0 {
  		return nil, err
  	}
  
  	newState := oldState.termios
  	newState.Iflag &^= syscall.ISTRIP | syscall.INLCR | syscall.ICRNL | syscall.IGNCR | syscall.IXON | syscall.IXOFF
  	newState.Lflag &^= syscall.ECHO | syscall.ICANON | syscall.ISIG
  	if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(fd), ioctlWriteTermios, uintptr(unsafe.Pointer(&newState)), 0, 0, 0); err != 0 {
  		return nil, err
  	}
  
  	return &oldState, nil
  }
docs: // MakeRaw put the terminal connected to the given file descriptor into raw
  // mode and returns the previous state of the terminal so that it can be
  // restored.