def add(self, *items):
        for item in items:
            if not self._graph.has_node(item):
                self._graph.add_node(item)
        return self
Save the useful bits of instance state for tracking purposes.
dataset/ETHPy150Open openstack/taskflow/taskflow/patterns/unordered_flow.py/Flow.add--crossover with--dataset/ETHPy150Open BU-NU-CLOUD-SP16/Trusted-Platform-Module-nova/nova/compute/stats.py/Stats._extract_state_from_instance