old_contents: class Game():
      def __init__(self):
          self._rolls = [0] * 21
          self._current_roll = 0
  
      def roll(self, pins):
          self._rolls[self._current_roll] += pins
          self._current_roll += 1
  
      def score(self):
          score = 0
          for frame in range(0, 20, 2):
              if self._is_spare(frame):
                  score += 10 + self._rolls[frame + 2]
              else:
                  score += self._frame_score(frame)
          return score
  
      def _is_spare(self, frame):
          return self._rolls[frame] + self._rolls[frame + 1] == 10
  
      def _frame_score(self, frame):
          return self._rolls[frame] + self._rolls[frame + 1]
  
new_contents: class Game():
      def __init__(self):
          self._rolls = [0] * 21
          self._current_roll = 0
  
      def roll(self, pins):
          self._rolls[self._current_roll] += pins
          self._current_roll += 1 if pins < 10 else 2
  
      def score(self):
          score = 0
          for frame in range(0, 20, 2):
              if self._is_strike(frame):
                  score += 10 + self._rolls[frame + 2] + self._rolls[frame + 3]
              elif self._is_spare(frame):
                  score += 10 + self._rolls[frame + 2]
              else:
                  score += self._frame_score(frame)
          return score
  
      def _is_spare(self, frame):
          return self._rolls[frame] + self._rolls[frame + 1] == 10
  
      def _is_strike(self, frame):
          print(frame)
          return self._rolls[frame] == 10
  
      def _frame_score(self, frame):
          return self._rolls[frame] + self._rolls[frame + 1]
  
subject: Add strikes support when rolling