Before revision:  PAGE is easy to implement as it is designed via a small adjustment to vanilla SGD: in each iteration, PAGE uses the vanilla minibatch SGD update with probability p and reuses the previous gradient with a small adjustment, at a much lower computational cost, with probability 1-p.
After revision:  PAGE is easy to implement as it is designed via a small adjustment to vanilla SGD: in each iteration, PAGE uses the vanilla minibatch SGD update with probability p or reuses the previous gradient with a small adjustment, at a much lower computational cost, with probability 1-p.