I have studied the reinforcement learning book by prof. Sutton. He provided the pseudo code of "*prioritized sweeping*" algorithm but I do not know what is the meaning of `Model(s,a)`. Does it mean that Model(s,a) just the history of rewards gaind when we are in state `s` and actio `a` is taken? 

`R,S_new = Model(s,a)`

Does the above line mean that we should take a random sample from rewards gained in state `s` and action `a` is taken?