new_contents: def checkio(game_result):
      return "D" or "X" or "O"
  
  if __name__ == '__main__':
      #These "asserts" using only for self-checking and not necessary for auto-testing
      assert checkio([
          "X.O",
          "XX.",
          "XOO"]) == "X", "Xs wins"
      assert checkio([
          "OO.",
          "XOX",
          "XOX"]) == "O", "Os wins"
      assert checkio([
          "OOX",
          "XXO",
          "OXX"]) == "D", "Draw"
      assert checkio([
          "O.X",
          "XX.",
          "XOO"]) == "X", "Xs wins again"
      print("Coding complete? Click 'Check' to review your tests and earn cool rewards!")
  
  '''
  Tic-Tac-Toe, sometimes also known as Xs and Os, is a game for two players (X and O) who take turns marking the spaces in a 3×3 grid. The player who succeeds in placing three respective marks in a horizontal, vertical, or diagonal rows (NW-SE and NE-SW) wins the game.
  
  But we will not be playing this game. You will be the referee for this games results. You are given a result of a game and you must determine if the game ends in a win or a draw as well as who will be the winner. Make sure to return "X" if the X-player wins and "O" if the O-player wins. If the game is a draw, return "D".
  
  x-o-referee
  
  A game's result is presented as a list of strings, where "X" and "O" are players' marks and "." is the empty cell.
  
  Input: A game result as a list of strings (unicode).
  
  Output: "X", "O" or "D" as a string.
  
  Example:
  
  checkio([
      "X.O",
      "XX.",
      "XOO"]) == "X"
  checkio([
      "OO.",
      "XOX",
      "XOX"]) == "O"
  checkio([
      "OOX",
      "XXO",
      "OXX"]) == "D"
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  How it is used: The concepts in this task will help you when iterating data types. They can also be used in game algorithms, allowing you to know how to check results.
  '''
subject: add next puzzel