code: def test_vjp(x_, dtype, func_str, backend_fw, nested_structs):
      if backend_fw == "numpy":
          pytest.skip()
  
      with BackendHandler.update_backend(backend_fw) as ivy_backend:
          base_func = ivy_backend.__dict__[func_str]
          if nested_structs == "none":
              primals, tangents = _get_primals_and_tangents(
                  x_, dtype, ivy_backend, False, False
              )
              func = base_func
          elif nested_structs == "nested_input_nested_output":
              primals, tangents = _get_primals_and_tangents(
                  x_, dtype, ivy_backend, True, True
              )
              func = base_func
          elif nested_structs == "nested_input_flat_output":
              primals, tangents = _get_primals_and_tangents(
                  x_, dtype, ivy_backend, True, False
              )
  
              def func(x):
                  return base_func(x["l"]["a"]) + base_func(x["l"]["b"])
  
          primals = (primals,)
          tangents = (tangents,)
          primals_out, vjp_fn = ivy_backend.vjp(func, *primals)
          vjp = vjp_fn(*tangents)
          flat_primals_np = helpers.flatten_and_to_np(
              ret=primals_out, backend=backend_fw
          )
          vjp_np = helpers.flatten_and_to_np(
              ret=vjp, backend=backend_fw
          )
          assert vjp_np != []
  
      with BackendHandler.update_backend("jax") as gt_backend:
          base_func = gt_backend.__dict__[func_str]
          if nested_structs == "none":
              primals, tangents = _get_primals_and_tangents(
                  x_, dtype, gt_backend, False, False
              )
              func = base_func
          elif nested_structs == "nested_input_nested_output":
              primals, tangents = _get_primals_and_tangents(
                  x_, dtype, gt_backend, True, True
              )
              func = base_func
          elif nested_structs == "nested_input_flat_output":
              primals, tangents = _get_primals_and_tangents(
                  x_, dtype, gt_backend, True, False
              )
  
              def func(x):
                  return base_func(x["l"]["a"]) + base_func(x["l"]["b"])
  
          primals = (primals,)
          tangents = (tangents,)
          primals_out_gt, vjp_fn = gt_backend.vjp(func, *primals)
          vjp = vjp_fn(*tangents)
          flat_primals_np_from_gt = helpers.flatten_and_to_np(
              ret=primals_out_gt, backend="jax"
          )
          vjp_np_from_gt = helpers.flatten_and_to_np(
              ret=vjp, backend="jax"
          )
          assert vjp_np_from_gt != []
  
      assert np.allclose(flat_primals_np, flat_primals_np_from_gt)
      assert np.allclose(vjp_np, vjp_np_from_gt)
  
file_path: ivy/ivy_tests/test_ivy/test_functional/test_experimental/test_core/test_gradients.py
imports: import pytest
  import numpy
  import ivy_tests.test_ivy.helpers
  from ivy_tests.test_ivy.helpers.pipeline_helper import BackendHandler
label_desc: Use image node_id 4 for calling a global function with example usage: test_vjp(x_, dtype, func_str, backend_fw, nested_structs) and returns: unknown, unknown