code: def basic_network(x):
      return mb.relu(x=x)
  
file_path: coremltools/coremltools/converters/mil/backend/mil/test_model_input_params.py
imports: import numpy
  import coremltools
  from coremltools.converters.mil.mil.builder import Builder
  from coremltools.converters.mil.mil.program import Symbol
  from coremltools.models.utils import _macos_version
label_desc: Use image node_id 1 for calling the TestMILFlexibleShapes obj's underlying member method code with example usage: obj.basic_network(x) and returns: mb