code: def polarity(self):
          
          self._polarity, value = self.get_attr_string(self._polarity, 'polarity')
          return value
docs: Sets the polarity of the motor. With `normal` polarity, a positive duty
          cycle will cause the motor to rotate clockwise. With `inversed` polarity,
          a positive duty cycle will cause the motor to rotate counter-clockwise.
          Valid values are `normal` and `inversed`.