code: def cdf(self, y, f):
          r
          mu = np.exp(f) if self.tranfcn == 'exp' else softplus(f)
          return poisson.cdf(y, mu=mu)
docs: r"""
          Cumulative density function of the likelihood.
  
          Parameters
          ----------
          y: ndarray
              query quantiles, i.e.\  :math:`P(Y \leq y)`.
          f: ndarray
              latent function from the GLM prior (:math:`\mathbf{f} =
              \boldsymbol\Phi \mathbf{w}`)
  
          Returns
          -------
          cdf: ndarray
              Cumulative density function evaluated at y.