class_docstr: Dropout regularization.
class_docstr_tok: ["Dropout","regularization","."]
code: def backward(self, x, gy):
      if chainer.should_use_cudnn(">=auto", 5000) and self._use_cudnn:
          return DropoutGradCuDNN(
              self.states, self.dropout_ratio
          ).apply(gy)
      else:
          return DropoutGrad(self.mask).apply(gy)
  
imports: import numpy
  import chainer
  from chainer.backends import cuda
  from chainer.backends import intel64
  from chainer import configuration
  from chainer import function_node
  from chainer.utils import argument
  from chainer.utils import type_check
label_desc: Use image node_id 6 for calling the Dropout obj's underlying member method code with example usage: obj.backward(x, gy) and returns: DropoutGradCuDNN, DropoutGrad