def tone(self):
        """
        Returns the :class:`~gpiozero.tones.Tone` that the buzzer is currently
        playing, or :data:`None` if the buzzer is silent. This property can
        also be set to play the specified tone.
        """
        if self.pwm_device.pin.frequency is None:
            return None
        else:
            return Tone.from_frequency(self.pwm_device.pin.frequency)