old_contents: # Player
  
  from common_definitions import BoardFieldType, BoardFieldCount, PlayerCount, PawnCount, Players
  
  
  class Player:
  
      def __init__(self, player):
          self.player = player
          print("New player: ", player)
  
      def move(self, number):
          pass
new_contents: # Player
  
  from common_definitions import Players
  
  
  class Player:
  
      def __init__(self, player):
          assert player in Players
  
          self.player = player
          print("New player: ", player)
  
      def move(self, number):
          pass
subject: Fix import and assertion