docs: def rate(totflux, pi, qminus):
      r"""Transition rate for reaction A to B.
  
      Parameters
      ----------
      totflux : float
          The total flux between reactant and product
      pi : (M,) ndarray
          Stationary distribution
      qminus : (M,) ndarray
          Backward comittor
  
      Returns
      -------
      kAB : float
          The reaction rate (per time step of the
          Markov chain)
  
      """
      kAB = totflux / (pi * qminus).sum()
      return kAB