code: function writeFlushed() {
            ee.emit('written', { total: obj.total, time: obj.time, batch: obj.batch });
            if (logCompletedBatch) {
              logCompletedBatch(obj.batch);
            }
            debug(' backed up batch', obj.batch, ' docs: ', obj.total, 'Time', obj.time);
          }
docs: this may be too verbose to have as well as the "backed up" message debug(' received batch', obj.batch, ' docs: ', obj.total, 'Time', obj.time); Callback to emit the written event when the content is flushed