Navigate CSEL

void move(int direction, int distance) {
  switch (direction) {
    case 'n':
      current_room[Y] -= distance;
      break;
    case 's':
      current_room[Y] += distance;
      break;
    case 'e':
      current_room[X] += distance;
      break;
    case 'w':
      current_room[X] -= distance;
      break;
    default:
      throw invalid_argument("Invalid direction.");
  }
}