code: def sleep(self, duration: float) -> None:
      self.now += duration
  
imports: import asyncio
  import concurrent.futures
  import dataclasses
  import queue
  import threading
  from typing import TYPE_CHECKING, Iterable, Mapping, Tuple
  from unittest.mock import Mock, call
  import pytest
  from wandb.filesync.step_prepare import Request, RequestFinish, RequestPrepare, ResponsePrepare, StepPrepare, gather_batch
label_desc: Use image node_id 2 for calling the MockClock obj's underlying member method code with example usage: obj.sleep(duration) without return types