code: def _low_dim_sim(self, v, w, normalize=False, Y=None, idx=0):
          
  
          sim = (1 + np.linalg.norm(v - w) ** 2) ** -1
  
          if normalize:
              return sim / sum(map(lambda x: x[1], self._knn(idx, Y, high_dim=False)))
          else:
              return sim
docs: Similarity measurement based on (Student) t-Distribution