<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def invert_differencing(self, initial_part, differenced_rest, order=None):
 """ function to invert the differencing """


        if order is None: order = self.diff_order

        # compute the differenced values of the initial part:
        starting_points = [ self.apply_differencing(initial_part, order=order)[-1] for order in range(self.diff_order)]
        
        actual_predictions = differenced_rest
        import pdb
        pdb.set_trace()
        for s in starting_points[::-1]:
            actual_predictions = np.cumsum(np.hstack([s, actual_predictions]))[1:]

        return(actual_predictions)