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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_reftrack(self, reftrack):
 """Add a reftrack object to the root. This will not handle row insertion in the model! It is automatically done when setting the parent of the :class:`Reftrack` object. :param reftrack: the reftrack object to add :type reftrack: :class:`Reftrack` :returns: None :rtype: None :raises: None """

        self._reftracks.add(reftrack)
        refobj = reftrack.get_refobj()
        if refobj:
            self._parentsearchdict[refobj] = reftrack