text: #include<string>
  #include<vector>
  
  using std::string; using std::vector;
  
  #include<iostream>
  
  using std::ostream; using std::istream;
  
  //h
  /*
  Represents one game of tic tac toe.
  */
  class TicTacToe 
  {
  public:
  	bool game_over();
  	void start_game(string player);
  	void mark_board(int position);
  	string get_player() const;
  	friend ostream& operator<<(ostream& out, const TicTacToe& t);
  	friend istream& operator>>(istream& in, TicTacToe& t);
  
  private:
  	void set_next_player();
  	bool check_column_win();
  	bool check_row_win();
  	bool check_diagonal_win();
  	void clear_board();
  	bool check_board_full();
  	vector<string> pegs{ 9, " " };//initializer
  	string next_player;
  };