code: def test_builder_to_backend_smoke(self, use_cpu_only, backend):
      t = np.array([[-1, 2, -3], [4, -5, 6]], dtype=np.float32)
      input_placeholders = {"x": mb.placeholder(shape=t.shape)}
      input_values = {"x": t}
  
      def build(x):
          return mb.softplus(x=x)
  
      expected_output_types = (2, 3, types.fp32)
      expected_outputs = np.array(
          [
              [0.31326166, 2.126928, 0.04858733],
              [4.01815, 0.00671535, 6.0024757],
          ],
          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 scipy import special
  import scipy
  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 TestSoftplus obj's underlying member method code with example usage: obj.test_builder_to_backend_smoke(use_cpu_only, backend) and returns: mb