def pre_tasks_serialize(self, nodes):
        """Serialize tasks for pre_deployment hook

        :param nodes: list of node db objects
        """
        if 'deploy_start' in self.graph:
            subgraph = self.graph.find_subgraph(end='deploy_start')
        else:
            raise errors.NotEnoughInformation(
                '*deploy_start* stage must be provided')
        return self.stage_tasks_serialize(subgraph.topology, nodes)
dataset/ETHPy150Open openstack/fuel-web/nailgun/nailgun/orchestrator/orchestrator_graph.py/AstuteGraph.pre_tasks_serialize/original