code: def equalspairs(X, Y):
      T = Y.copy()
      R = (T[1:] != T[:-1]).nonzero()[0]
      R = np.append(R,np.array([len(T)-1]))
      M = R[R.searchsorted(range(len(T)))]
      D = T.searchsorted(X)
      T = np.append(T,np.array([0]))
      M = np.append(M,np.array([0]))
      A = (T[D] == X) * D
      B = (T[D] == X) * (M[D] + 1)
      return [A,B]