docs: def past_heating_level(self, num):
          """Return a heating level from the past."""
          if num > 9:
              return 0
  
          try:
              if self.side == 'left':
                  level = self.device.device_data_history[
                      num]['leftHeatingLevel']
              elif self.side == 'right':
                  level = self.device.device_data_history[
                      num]['rightHeatingLevel']
              return level
          except TypeError:
              return 0