code: def _kendall_tau_diff(self, a: np.ndarray, b: np.ndarray, i) -> Tuple[int, int]:
          
          # compute ordering relation of the single points a[i] and b[i]
          # with all previous points of the sequences a and b, respectively
          a_pos = np.zeros(a[:i].size, dtype=int)
          a_pos[a[:i] > a[i]] = 1
          a_pos[a[:i] < a[i]] = -1
          b_pos = np.zeros(b[:i].size, dtype=int)
          b_pos[b[:i] > b[i]] = 1
          b_pos[b[:i] < b[i]] = -1
          diff_pos = np.dot(a_pos, b_pos).astype(float)
  
          # compute ordering relation of the single points a[i] and b[i]
          # with all later points of the sequences
          a_neg = np.zeros(a[i:].size, dtype=int)
          a_neg[a[i:] > a[i]] = 1
          a_neg[a[i:] < a[i]] = -1
          b_neg = np.zeros(b[i:].size, dtype=int)
          b_neg[b[i:] > b[i]] = 1
          b_neg[b[i:] < b[i]] = -1
          diff_neg = np.dot(a_neg, b_neg)
  
          return diff_pos, diff_neg
docs: Compute difference in concordance of pairs in split sequences.
  
          Consider splitting a and b at index i.
  
          Parameters
          ----------
          a
              ?
          b
              ?
  
          Returns
          -------
          diff_pos
              Difference between concordant pairs for both subsequences.
          diff_neg
              Difference between non-concordant pairs for both subsequences.