void SetConsoleEcho(bool on) {
#ifdef WIN32
  HANDLE hIn = GetStdHandle(STD_INPUT_HANDLE);
  if ((hIn == INVALID_HANDLE_VALUE) || (hIn == NULL))
    return;

  DWORD mode;
  if (!GetConsoleMode(hIn, &mode))
    return;

  if (on) {
    mode = mode | ENABLE_ECHO_INPUT;
  } else {
    mode = mode & ~ENABLE_ECHO_INPUT;
  }

  SetConsoleMode(hIn, mode);
#else
  if (on)
    system("stty echo");
  else
    system("stty -echo");
#endif
}