code: def _IsProtoClass(obj):
      """Returns whether the passed obj is a Protocol Buffer class."""
      return isinstance(obj, type) and issubclass(obj, message.Message)
  
file_path: tensorflow/tensorflow/tools/api/lib/python_object_to_proto_visitor.py
imports: import enum
  import re
  import sys
  from google.protobuf import message
  from tensorflow.python.platform import tf_logging
  from tensorflow.python.util import deprecation
  from tensorflow.python.util import tf_decorator
  from tensorflow.python.util import tf_inspect
  from tensorflow.tools.api.lib import api_objects_pb2
label_desc: Use image node_id 7 for calling a global function with example usage: _IsProtoClass(obj) and returns: unknown