def addNode(self, node1, node2):
        if not node1 and not node2:
            raise Exception("two nodes are None")
        if not node1:
            return node2.val
        if not node2:
            return node1.val
        return node1.val+node2.val
Pump until there is no more input or output.
dataset/ETHPy150Open algorhythms/LeetCode/004 Add Two Numbers.py/Solution.addNode--crossover with--dataset/ETHPy150Open kuri65536/python-for-android/python-modules/twisted/twisted/test/iosim.py/IOPump.flush