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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 add_deviation(self, dev, td=None):
 """ Add a deviation survey to this instance, and try to compute a position log from it. """

        self.deviation = dev
        try:
            self.compute_position_log(td=td)
        except:
            self.position = None
        return