code: def test_backward_gpu(self):
      self.check_backward(
          cuda.to_gpu(self.logit),
          cuda.to_gpu(self.x),
          cuda.to_gpu(self.gy),
      )
  
imports: import unittest
  import numpy
  from chainer import backend
  from chainer.backends import cuda
  from chainer import distributions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
label_desc: Use image node_id 7 for calling the TestBernoulliLogProb obj's underlying member method code with example usage: obj.test_backward_gpu() without return types