old_contents: #!/usr/bin/env python
  from abc import ABCMeta, abstractmethod
  from game.gameboard import GameBoard
  
  class Player(object):
      __metaclass__ = ABCMeta
  
      def __init__(self, color):
          self._color = color.lower()
  
      def color(self):
          return self._color
  
      def is_winner(self, board):
          if board.game_over() and board.winner_color() == self._color:
              return True
          return False
  
      @abstractmethod
      def play(self):
          """This method must be overridden"""
          pass
  
  class PlayerWithStrategyOne(Player):
      def play(self, board):
          board.put_chip(board.retrieve_first_non_full_column(), self._color)
  
  class PlayerWithStrategyTwo(Player):
      def play(self, board):
          board.put_chip(board.retrieve_emptiest_column(), self._color)
  
new_contents: #!/usr/bin/env python
  from abc import ABCMeta, abstractmethod
  from game.gameboard import GameBoard
  
  class Player(object):
      __metaclass__ = ABCMeta
  
      def __init__(self, color):
          self._color = color.lower()
  
      def color(self):
          return self._color
  
      def is_winner(self, board):
          return board.game_over() and board.winner_color() == self._color
  
      @abstractmethod
      def play(self):
          """This method must be overridden"""
          pass
  
  class PlayerWithStrategyOne(Player):
      def play(self, board):
          board.put_chip(board.retrieve_first_non_full_column(), self._color)
  
  class PlayerWithStrategyTwo(Player):
      def play(self, board):
          board.put_chip(board.retrieve_emptiest_column(), self._color)
  
subject: Replace the particular boolean returns with a boolean expression on is_winner