code: def test_builder_to_backend_smoke(self, use_cpu_only, backend):
      x = np.array([[1, 2, 3], [4, 5, 6]], dtype=np.float32)
      indices = np.array([[1, 0], [0, 2]], dtype=np.int32)
      input_placeholders = {
          "x": mb.placeholder(shape=x.shape),
          "indices": mb.placeholder(
              shape=indices.shape, dtype=types.int32
          ),
      }
  
      input_values = {"x": x, "indices": indices}
  
      def build(x, indices):
          return (mb.gather_nd(x=x, indices=indices),)
  
      expected_output_types = (2, types.fp32)
      expected_outputs = np.array([4, 3], dtype=np.float32)
  
      run_compare_builder(
          build,
          input_placeholders,
          input_values,
          expected_output_types,
          expected_outputs,
          use_cpu_only=use_cpu_only,
          frontend_only=False,
          backend=backend,
      )
  
imports: from coremltools.converters.mil import testing_reqs
  from coremltools.converters.mil.testing_reqs import *
  from .testing_utils import run_compare_builder
label_desc: Use image node_id 1 for calling the TestGatherNd obj's underlying member method code with example usage: obj.test_builder_to_backend_smoke(use_cpu_only, backend) and returns: mb