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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 set_id(self, identifier):
 """Set the id of the given reftrack This will set the id on the refobject :param identifier: the identifier number :type identifier: int :returns: None :rtype: None :raises: None """

        self._id = identifier
        refobj = self.get_refobj()
        if refobj:
            self.get_refobjinter().set_id(refobj, identifier)