code: def test_invalid_dtype_gpu(self):
      self.v.to_gpu()
      with self.assertRaises(type_check.InvalidType):
          self.check_invalid_dtype()
  
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
  from chainer.testing import condition
  from chainer.utils import type_check
  from chainer_tests.functions_tests.pooling_tests import pooling_nd_helper
label_desc: Use image node_id 4 for calling the TestInvalidDtype obj's underlying member method code with example usage: obj.test_invalid_dtype_gpu() without return types