code: def __init__(self, message: str):
      print("Echo message:", message)
      self._message = message
  
file_path: ray/python/ray/serve/tests/test_config_files/arg_builders.py
imports: from ray import serve
  from ray._private.pydantic_compat import BaseModel
label_desc: Use image node_id 1 to create a new Echo object  with example: obj = Echo(message)