MI GRBL Z-AXIS Servo controller extension work

The MI GRBL Z-AXIS Servo controller extension throws an error. Inkscape received additional data from the executed script. This may mean that the results will be different than expected.

Traceback (most recent call last):
  File "servo.py", line 3172, in <module>
    e.affect ()
  File "C: \ Program Files \ Inkscape \ share \ extensions \ inkex.py", line 268, in affect
    self.effect ()
  File "servo.py", line 3156, in effect
    self.orientation (self.layers [min (0, len (self.layers) -1)])
  File "servo.py", line 3085, in orientation
    doc_height = inkex.unittouu (self.document.getroot (). get ('height'))
AttributeError: 'module' object has no attribute 'unittouu'