class_docstr: Platform-independent emitter that polls a directory to detect file
  system changes.
class_docstr_tok: ["Platform-independent","emitter","that","polls","a","directory","to","detect","file","system","changes","."]
code: def on_thread_start(self):
      self._snapshot = self._take_snapshot()
  
file_path: wandb/wandb/vendor/watchdog_0_9_0/wandb_watchdog/observers/polling.py
imports: from __future__ import with_statement
  import os
  import threading
  from functools import partial
  from wandb_watchdog.utils import stat
  from wandb_watchdog.utils.dirsnapshot import DirectorySnapshot, DirectorySnapshotDiff
  from wandb_watchdog.observers.api import EventEmitter, BaseObserver, DEFAULT_OBSERVER_TIMEOUT, DEFAULT_EMITTER_TIMEOUT
  from wandb_watchdog.events import DirMovedEvent, DirDeletedEvent, DirCreatedEvent, DirModifiedEvent, FileMovedEvent, FileDeletedEvent, FileCreatedEvent, FileModifiedEvent
label_desc: Use image node_id 2 for calling the PollingEmitter obj's underlying member method code with example usage: obj.on_thread_start() without return types