text: # coding=utf-8
  # Copyright 2021 The Google Research Authors.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  # Lint as: python3
  """VisionDataset that allows user to get example indices."""
  
  import torchvision
  
  
  class VisionDatasetWithIndices(torchvision.datasets.vision.VisionDataset):
    """VisionDataset that allows user to get example indices.
  
    Dataset that returns a triple (data, targets, indices)
    instead of just (data, targets). Indices of training examples can be
    used to track model performance on individual examples, for instance to find
    training examples that are learned faster than others.
    """
  
    def __init__(self, dataset):
      super(VisionDatasetWithIndices, self).__init__(None)
      self.dataset = dataset
  
    def __getitem__(self, index):
      data, target = self.dataset.__getitem__(index)
      return data, target, index
  
    def __len__(self):
      return len(self.dataset)
  