code: def backward(self, speed=1):
          
          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
docs: 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).