class_docstr: An exception to throw if user input is detected to be invalid.
  
  Attributes:
    original_exception: The triggering `Exception` object to be wrapped, or
      a string.
code: def message(self):
      return "InvalidUserInputError: " + str(self.original_exception)
  
file_path: what-if-tool/utils/common_utils.py
imports: from tensorflow_serving.apis import classification_pb2
  from tensorflow_serving.apis import regression_pb2
label_desc: Use image node_id 2 for calling the InvalidUserInputError obj's underlying member method code with example usage: obj.message() and returns: unknown