old_contents: import numpy as np
  from gensim import matutils
  from gensim.corpora import Dictionary
  
  
  class BaseVectorizer:
      """Base class for vectorization objects. """
      name = NotImplemented
  
      def transform(self, corpus, copy=True):
          """Transforms a corpus to a new one with additional attributes. """
          if copy:
              corpus = corpus.copy()
  
          if not len(corpus.dictionary):
              return corpus
          else:
              return self._transform(corpus)
  
      def _transform(self, corpus):
          raise NotImplementedError
  
      def report(self):
          """Reports configuration items."""
          raise NotImplementedError
  
      @staticmethod
      def add_features(corpus, X, dictionary):
          order = np.argsort([dictionary[i] for i in range(len(dictionary))])
          corpus.extend_attributes(X[:, order],
                                   feature_names=(dictionary[i] for i in order),
                                   var_attrs={'hidden': True})
          corpus.ngrams_corpus = matutils.Sparse2Corpus(X.T)
  
new_contents: import numpy as np
  from gensim import matutils
  from gensim.corpora import Dictionary
  
  
  class BaseVectorizer:
      """Base class for vectorization objects. """
      name = NotImplemented
  
      def transform(self, corpus, copy=True):
          """Transforms a corpus to a new one with additional attributes. """
          if copy:
              corpus = corpus.copy()
  
          if not len(corpus.dictionary):
              return corpus
          else:
              return self._transform(corpus)
  
      def _transform(self, corpus):
          raise NotImplementedError
  
      def report(self):
          """Reports configuration items."""
          raise NotImplementedError
  
      @staticmethod
      def add_features(corpus, X, dictionary):
          order = np.argsort([dictionary[i] for i in range(len(dictionary))])
          corpus.extend_attributes(X[:, order],
                                   feature_names=(dictionary[i] for i in order),
                                   var_attrs={'hidden': True, 'skip-normalization': True})
          corpus.ngrams_corpus = matutils.Sparse2Corpus(X.T)
  
subject: Mark features to skip normalization