In PyTorch, there are multiple capabilities with respect to the SGD optimizer. Setting the momentum parameter to 0 gives you standard SGD. If momentum > 0, then you use momentum without the lookahead i.e., Classical Momentum. nesterov is a bool, which if set to true, provides the look ahead which is know as Nesterov’s Accelerated Gradient.
You may want to look up the implementation here 375.