code: def mb_neg_logposterior(self, beta, mini_batch):
          
  
          post = (self.data.shape[0]/mini_batch)*self.mb_neg_loglik(beta, mini_batch)
          for k in range(0,self.z_no):
              post += -self.latent_variables.z_list[k].prior.logpdf(beta[k])
          return post
docs: Returns negative log posterior
  
          Parameters
          ----------
          beta : np.array
              Contains untransformed starting values for latent variables
  
          mini_batch : int
              Batch size for the data
  
          Returns
          ----------
          Negative log posterior