code: def test_immutable(self, backend_config):
      self.check_immutable(self.inputs, backend_config)
  
imports: import unittest
  import numpy
  import chainer
  from chainer.backends import cuda
  from chainer import functions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
label_desc: Use image node_id 10 for calling the TestDropout obj's underlying member method code with example usage: obj.test_immutable(backend_config) without return types