code: def _get_testloader(net, test_dataset, num_devices, config):
      """Get faster rcnn test dataloader."""
      if config.meta_arch == "faster_rcnn":
          test_bfn = Tuple(*[Append() for _ in range(3)])
          short = (
              net.short[-1]
              if isinstance(net.short, (tuple, list))
              else net.short
          )
          # validation use 1 sample per device
          test_loader = gluon.data.DataLoader(
              test_dataset.transform(
                  FasterRCNNDefaultValTransform(short, net.max_size)
              ),
              num_devices,
              False,
              batchify_fn=test_bfn,
              last_batch="keep",
              num_workers=config.num_workers,
          )
          return test_loader
      else:
          raise NotImplementedError(
              "%s not implemented." % config.meta_arch
          )
  
file_path: gluon-cv/gluoncv/auto/estimators/faster_rcnn/utils.py
imports: import os
  from mxnet import gluon
  from ....data.batchify import FasterRCNNTrainBatchify, Tuple, Append
  from ....data.sampler import SplitSortedBucketSampler
  from ....data.transforms.presets.rcnn import FasterRCNNDefaultValTransform
  from ....None import data
  from ....utils.metrics.coco_detection import COCODetectionMetric
  from ....utils.metrics.voc_detection import VOC07MApMetric
label_desc: Use image node_id 5 for calling a global function with example usage: _get_testloader(net, test_dataset, num_devices, config) and returns: test_loader