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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 _propagate_up(self, handle, target_id, name=None):
 """ In a non-master context, propagate an update towards the master. :param int handle: :data:`mitogen.core.ADD_ROUTE` or :data:`mitogen.core.DEL_ROUTE` :param int target_id: ID of the connecting or disconnecting context. :param str name: For :data:`mitogen.core.ADD_ROUTE`, the name of the new context assigned by its parent. This is used by parents to assign the :attr:`mitogen.core.Context.name` attribute. """

        if self.parent:
            stream = self.router.stream_by_id(self.parent.context_id)
            self._send_one(stream, handle, target_id, name)