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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 inc(self):
 """Corrected inclination, taking into account backsight and clino corrections."""

        inc1 = self.get('INC', None)
        inc2 = self.get('INC2', None)
        if inc1 is None and inc2 is None:
            return None
        if inc2 is None:
            return inc1
        if inc1 is None:
            return -1 * inc2
        return (inc1 - inc2) / 2.0