code: def test_builder_stress(self, compute_unit, backend, config):
      source_val, output_dtype = (
          config["source_val"],
          config["output_dtype"],
      )
  
      def build(x):
          y = mb.constexpr_cast(
              source_val=source_val,
              output_dtype=output_dtype,
          )
          return mb.add(x=x, y=y)
  
      expected_output_types = (
          *source_val.shape,
          types.string_to_builtin(output_dtype),
      )
  
      output_np_type = types.nptype_from_builtin(
          types.string_to_builtin(output_dtype)
      )
      t = np.random.rand(*source_val.shape).astype(output_np_type)
      decompressed_constant = source_val.astype(output_np_type)
      expected_outputs = t + decompressed_constant
  
      input_placeholders = {
          "x": mb.placeholder(shape=source_val.shape),
      }
      input_values = {"x": t}
      mlmodel = run_compare_builder(
          build,
          input_placeholders,
          input_values,
          expected_output_types,
          expected_outputs,
          compute_unit=compute_unit,
          backend=backend,
      )
  
      # validate that the constexpr op is not removed by any graph pass
      prog = mlmodel._mil_program
      assert "constexpr_cast" in get_op_types_in_program(prog)
  
imports: import itertools
  import numpy
  import pytest
  from coremltools.converters.mil import testing_reqs
  from coremltools.converters.mil.mil import Builder
  from coremltools.converters.mil.mil import types
  from coremltools.converters.mil.mil.ops.defs.iOS16 import constexpr_ops
  from coremltools.converters.mil.mil.ops.tests.iOS16 import backends
  from coremltools.converters.mil.mil.ops.tests.testing_utils import run_compare_builder
  from coremltools.converters.mil.testing_utils import get_op_types_in_program, ssa_fn
label_desc: Use image node_id 4 for calling the TestConstexprCast obj's underlying member method code with example usage: obj.test_builder_stress(compute_unit, backend, config) and returns: mb