new_contents: # coding: utf-8
  
  # Author: Hussein AL-NATSHEH <hussein.al-natsheh@ish-lyon.cnrs.fr>
  # License: BSD 3 clause
  # 2016
  
  from sklearn.metrics.pairwise import cosine_similarity
  import numpy as np
  
  from sklearn.base import BaseEstimator
  from sklearn.base import TransformerMixin
  
  class PairCosine(BaseEstimator, TransformerMixin):
      """Cosine similarity on paired data."""
  
      def fit(self, X, y=None):
          """(Do nothing).
  
          Parameters
          ----------
          :param X: array-like, shape (n_pair, 2)
              Input data.
  
          Returns
          -------
          :returns: self
          """
          return self
  
      def transform(self, X):
          """Compute the cosine similarity of all pairs in ``X``.
  
          To be added.
  
          Parameters
          ----------
          :param X: array-like, shape (n_pair, 2)
              Input paired data.
  
          Returns
          -------
          :returns Xt: array-like, shape (n_pair, 1)
              The transformed data.
          """
          n_pairs, two = X.shape
          Xt = np.zeros(n_pairs, dtype=float)
          i=0
          for x1, x2 in X:
              Xt[i] = cosine_similarity(x1, x2)
              i+=1
  
          return Xt.reshape(n_pairs, 1)
  
subject: add a missing file: combiners.py