class_docstr: TensorBoardX Logger.
  
  Note that hparams will be written only after a trial has terminated.
  This logger automatically flattens nested dicts to show on TensorBoard:
  
      {"a": {"b": 1, "c": 2}} -> {"a/b": 1, "a/c": 2}
code: def flush(self):
      if self._file_writer is not None:
          self._file_writer.flush()
  
imports: import logging
  import numpy
  from typing import TYPE_CHECKING, Dict
  from ray.air.constants import TRAINING_ITERATION
  from ray.tune.logger.logger import _LOGGER_DEPRECATION_WARNING, Logger, LoggerCallback
  from ray.util.debug import log_once
  from ray.tune.result import TIME_TOTAL_S, TIMESTEPS_TOTAL
  from ray.tune.utils import flatten_dict
  from ray.util.annotations import Deprecated, PublicAPI
label_desc: Use image node_id 3 for calling the TBXLogger obj's underlying member method code with example usage: obj.flush() without return types