code: def get_file_stream_api(self):
          
          if not self._file_stream_api:
              if self._current_run_id is None:
                  raise UsageError(
                      'Must have a current run to use file stream API.')
              self._file_stream_api = FileStreamApi(self, self._current_run_id)
          return self._file_stream_api
docs: This creates a new file pusher thread.  Call start to initiate the thread that talks to W&B