src/transformers/integrations.py/TensorBoardCallback/_init_summary_writer
class TensorBoardCallback:    def _init_summary_writer(self, args, log_dir=None):
        log_dir = log_dir or args.logging_dir
        if self._SummaryWriter is not None:
            self.tb_writer = self._SummaryWriter(log_dir=log_dir)