docs: def _process_cell(i, state, finite=False):
      """Process 3 cells and return a value from 0 to 7. """
      op_1 = state[i - 1]
      op_2 = state[i]
      if i == len(state) - 1:
          if finite:
              op_3 = state[0]
          else:
              op_3 = 0
      else:
          op_3 = state[i + 1]
      result = 0
      for i, val in enumerate([op_3, op_2, op_1]):
          if val:
              result += 2**i
      return result