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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 parent(self):
 """The parent of the current key. :rtype: :class:`google.cloud.datastore.key.Key` or :class:`NoneType` :returns: A new ``Key`` instance, whose path consists of all but the last element of current path. If the current key has only one path element, returns ``None``. """

        if self._parent is None:
            self._parent = self._make_parent()

        return self._parent