old_contents: import os # for reading files and directories
  import numpy as np # for arrays
  
  """ReadDataset: reads dataset images and labels into numpy arrays.
                  Also, an optional normalization can be applied over all the data."""
  class ReadDataset:
  
      def __init__(self, dataset, path=None, normalize=True):
          """__dataset = (str) dataset type: ['cub',  'oxford-102']
              __path = (str) path to the dataset. If not specified, it will look to 'datasets/{cub | oxford-102}'
              __normalization = (bool) if True, normalizes all the images of the dataset to be [-1, 1]."""
  
          # Check that dataset type is valid
          dataset = dataset.lower()
          assert dataset == 'cub' or dataset == 'oxford-102', "Dataset not recognized: %s. Must be 'cub' or 'oxford'" % dataset
          self.__dataset = dataset
  
          # Initialize path, if not specified
          if path is None:
              self.__path = 'dataset/'+self.__dataset
  
          self.__normalize = normalize
  
      def method(self):
          """Input:
                  - blabla:
             Output:
                  - blabla: """
          pass
  
  if __name__ == '__main__':
      pass
new_contents: import os # for reading files and directories
  import numpy as np # for arrays
  
  """ReadDataset: reads dataset images and labels into numpy arrays.
                  Also, an optional normalization can be applied over all the data."""
  class ReadDataset:
  
      def __init__(self, dataset, path=None, normalize=True):
          """__dataset = (str) dataset type: ['cub',  'oxford-102']
              __path = (str) path to the dataset. If not specified, it will look to 'datasets/{cub | oxford-102}'
              __normalization = (bool) if True, normalizes all the images of the dataset to be [-1, 1]."""
  
          # Check that dataset type is valid
          dataset = dataset.lower()
          assert dataset == 'cub' or dataset == 'oxford-102', "Dataset not recognized: %s. Must be 'cub' or 'oxford-102'" % dataset
          self.__dataset = dataset
  
          # Initialize path, if not specified
          if path is None:
              self.__path = 'dataset/'+self.__dataset
  
          self.__normalize = normalize
  
      def method(self):
          """Input:
                  - blabla:
             Output:
                  - blabla: """
          pass
  
  if __name__ == '__main__':
      pass
subject: Correct assert error message