code: def lifetimes(self):
          r
          return -self._lag / np.log(np.diag(self.transition_matrix))
docs: r""" Lifetimes of states of the hidden transition matrix
  
          Returns
          -------
          l : ndarray(nstates)
              state lifetimes in units of the input trajectory time step,
              defined by :math:`-tau / ln | p_{ii} |, i = 1,...,nstates`, where
              :math:`p_{ii}` are the diagonal entries of the hidden transition matrix.