def backward(start, end):
    return lambda x: df.th.grad(None, wrt=start, known_grads={end: x})
access to ``tornado.web.RequestHandler``
dataset/ETHPy150Open lucasb-eyer/DeepFried2/DeepFried2/containers/Backward.py/backward--crossover with--dataset/ETHPy150Open toastdriven/restless/restless/tnd.py/TornadoResource.r_handler