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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def backward(self, speed=1):
 """ Drive the motor backwards. :param float speed: The speed at which the motor should turn. Can be any value between 0 (stopped) and the default 1 (maximum speed). """

        if isinstance(self.enable_device, DigitalOutputDevice):
            if speed not in (0, 1):
                raise ValueError(
                    'backward speed must be 0 or 1 with non-PWM Motors')
        self.enable_device.off()
        self.phase_device.on()
        self.enable_device.value = speed