code: def IdentityForwardOnlyFunction_backward(inputs):
      raise NotImplementedError(
          "PassForwardOnlyFunction_backward is not implemented.\nThe expected behavior is that this function will not be called."
      )
  
imports: import sys
  import pytest
  import numpy
  import nnabla
  import nnabla.functions
  import nnabla.parametric_functions
  import nnabla.initializer
  from nnabla.ext_utils import get_extension_context
  from nbla_test_utils import list_context
  from nnabla.testing import assert_allclose
  from nnabla.function import PythonFunction
  from nnabla.backward_functions import registry, register
label_desc: Use image node_id 8 for calling a global function with example usage: IdentityForwardOnlyFunction_backward(inputs) without return types