class_docstr: Loader for an entire directory, maintaining multiple active file
  loaders.
  
  This class takes a directory, a factory for loaders, and optionally a
  path filter and watches all the paths inside that directory for new data.
  Each file loader created by the factory must read a path and produce an
  iterator of (timestamp, value) pairs.
  
  Unlike DirectoryWatcher, this class does not assume that only one file
  receives new data at a time; there can be arbitrarily many active files.
  However, any file whose maximum load timestamp fails an "active" predicate
  will be marked as inactive and no longer checked for new data.
docstr: If max_timestamp is inactive, returns True and marks the path as
  such.
code: def _MarkIfInactive(self, path, max_timestamp):
      """If max_timestamp is inactive, returns True and marks the path as
      such."""
      logger.debug(
          "Checking active status of %s at %s", path, max_timestamp
      )
      if max_timestamp is not None and not self._active_filter(
          max_timestamp
      ):
          self._max_timestamps[path] = _INACTIVE
          del self._loaders[path]
          return True
      return False
  
file_path: tensorboard/tensorboard/backend/event_processing/directory_loader.py
imports: from tensorboard.backend.event_processing import directory_watcher
  from tensorboard.backend.event_processing import io_wrapper
  from tensorboard.compat import tf
  from tensorboard.util import tb_logging
label_desc: Use image node_id 4 for calling the DirectoryLoader obj's underlying member method code with example usage: obj._MarkIfInactive(path, max_timestamp) and returns: False, True