with [torch.no_grad](https://docs.pytorch.org/docs/stable/generated/torch.no_grad.html#torch.no_grad "torch.no_grad")():
    for p in [model.parameters](https://docs.pytorch.org/docs/stable/generated/torch.nn.Module.html#torch.nn.Module.parameters "torch.nn.Module.parameters")(): p -= p.grad * lr
    [model.zero_grad](https://docs.pytorch.org/docs/stable/generated/torch.nn.Module.html#torch.nn.Module.zero_grad "torch.nn.Module.zero_grad")()