code: def test_sinc_double_backward(seed, ctx, func_name):
      from nbla_test_utils import backward_function_tester
  
      rng = np.random.RandomState(seed)
      inputs = [rng.randn(2, 3, 4).astype(np.float32) * 1]
      backward_function_tester(rng, F.sinc, inputs=inputs, 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_sinc_double_backward(seed, ctx, func_name) without return types