code: function getGameBeforeLastMove(game) {
      // $Fix I do NOT know if it is the best way to make game immutable.
      game = Object.assign({}, game);
      let lastMove = game.moves.pop();
      if (lastMove)
          game = getGameAfterMove(game, getBackMove(lastMove), true);
      if (Game.getPlayerTurn(game).isAi) {
          lastMove = game.moves.pop();
          if (lastMove) {
              game = getGameAfterMove(game, getBackMove(lastMove), true);
          }
      }
      return game;
  }
docs: Get game before last move,
  if playing vs Ai rollback Ai move too.