code: def random_draw(self, size=None):
          
          return scipy.asarray([scipy.stats.gamma.rvs(a, loc=0, scale=1.0 / b, size=size) for a, b in zip(self.a, self.b)])
docs: Draw random samples of the hyperparameters.
          
          Parameters
          ----------
          size : None, int or array-like, optional
              The number/shape of samples to draw. If None, only one sample is
              returned. Default is None.