anchor.diff:  class BoardGame {
     List playerOnePieces = [];
     List playerTwoPieces = [];
  +  void play() { print(this); }
     String get winner => new Random().nextBool() ? "Player One" : "Player Two";
     String toString() =>
       "  ${this.runtimeType}\n"
  -    "    Player One has: ${playerOnePieces.join(', ')}\n"
  -    "    Player Two has: ${playerTwoPieces.join(', ')}\n"
  +    "    Player One starts with: ${playerOnePieces.join(', ')}\n"
  +    "    Player Two starts with: ${playerTwoPieces.join(', ')}\n"
  +    "    --\n"
       "    Winner: $winner\n";
   }
   
  
positive.code: 
  main() {
    var series = new GameFactory('Professor Falken', 'Joshua');
    print(series);
  
    var game;
    game = series.createBoardGame('Checkers');
    print(game);
  
    game = series.createBoardGame('Thermo Nuclear War');
    print(game);
  
    game = series.createBoardGame();
    print(game);
  }
  
negative.code: class GameFactory {
    String playerOne, playerTwo;
    GameFactory(this.playerOne, this.playerTwo);
    void start() { print(this); }
    String toString() => "*** $playerOne vs. $playerTwo ***";
  
    // The factory method
  