def __radd__(self, y):
        for key, value in y.items():
            self[key] += value
L{Deferred} chaining is transitive.
dataset/ETHPy150Open rlpy/rlpy/rlpy/Domains/PacmanPackage/util.py/Counter.__radd__--crossover with--dataset/ETHPy150Open kuri65536/python-for-android/python-modules/twisted/twisted/test/test_defer.py/DeferredTestCase.test_doubleAsynchronousImplicitChaining