code: def serialize_function(function, concrete_functions):
      """Build a SavedFunction proto."""
      proto = saved_object_graph_pb2.SavedFunction()
  
      function_spec_proto = _serialize_function_spec(
          function.function_spec
      )
      proto.function_spec.CopyFrom(function_spec_proto)
      for concrete_function in concrete_functions:
          proto.concrete_functions.append(concrete_function.name)
      return proto
  
file_path: tensorflow/tensorflow/python/saved_model/function_serialization.py
imports: from tensorflow.core.function.polymorphism import function_type
  from tensorflow.core.protobuf import saved_object_graph_pb2
  from tensorflow.python.eager import function
  from tensorflow.python.eager import wrap_function
  from tensorflow.python.eager.polymorphic_function import function_type_utils
  from tensorflow.python.framework import func_graph
  from tensorflow.python.saved_model import nested_structure_coder
  from tensorflow.python.util import nest
label_desc: Use image node_id 5 for calling a global function with example usage: serialize_function(function, concrete_functions) and returns: proto