code: def test_elu_double_backward(seed, alpha, ctx, func_name):
      from nbla_test_utils import backward_function_tester
  
      rng = np.random.RandomState(seed)
      inputs = [rng.randn(2, 3).astype(np.float32) * 2]
      backward_function_tester(
          rng,
          F.elu,
          inputs=inputs,
          func_args=[alpha],
          func_kwargs={},
          atol_accum=1e-3,
          dstep=1e-3,
          ctx=ctx,
      )
  
imports: import pytest
  import numpy
  import nnabla.functions
  from nbla_test_utils import list_context
label_desc: Use image node_id 3 for calling a global function with example usage: test_elu_double_backward(seed, alpha, ctx, func_name) without return types