code: def __init__(self):
      self._event = asyncio.Event()
      self._lock = asyncio.Lock()
      self._version = 0
  
imports: import asyncio
  import enum
  import functools
  import time
  from dataclasses import dataclass, field
  from typing import AsyncGenerator, Awaitable, Callable, Dict, Optional, Set, Tuple, TypeVar
  from ...serialization.serializables import Serializable, Float64Field, Int32Field, Int64Field, StringField
  from ...storage import StorageLevel
  from ..core import NodeRole
label_desc: Use image node_id 1 to create a new WatchNotifier object  with example: obj = WatchNotifier()