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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 make_pilothole_cutter(self):
 """ Make a solid to subtract from an interfacing solid to bore a pilot-hole. """

        # get pilothole ratio
        #   note: not done in .initialize_parameters() because this would cause
        #   the thread's profile to be created at initialisation (by default).
        pilothole_radius = self.pilothole_radius
        if pilothole_radius is None:
            (inner_radius, outer_radius) = self.get_radii()
            pilothole_radius = inner_radius + self.pilothole_ratio * (outer_radius - inner_radius)

        return cadquery.Workplane('XY') \
            .circle(pilothole_radius) \
            .extrude(self.length)