code the first variable so here this is the algorithm for just as usual so here this is basically um decode Z and then encode X and then encode the prior so this is P of X given Z mmm-hmm and here Z given X what you can do instead is code just the first layer and then recursively invoke its back coding into the C the subsequent layers right and so the the consequence of doing this is that I won't go through these the exact steps but the consequence is that you no longer have to decode the entire block of latent