code: def arlognormal_like(x, a, sigma, rho):
      R
      return flib.arlognormal(x, np.log(a), sigma, rho, beta=1)
docs: R"""
      Autoregressive lognormal log-likelihood.
  
      .. math::
          x_i & = a_i \exp(e_i) \\
          e_i & = \rho e_{i-1} + \epsilon_i
  
      where :math:`\epsilon_i \sim N(0,\sigma)`.