The .module attribute will be added by nn.DataParallel for all models including nn.Seuqential:
model = nn.Sequential(
    nn.Linear(1, 1),
    nn.ReLU(),
    nn.Linear(1, 1))

model = nn.DataParallel(model)
print(model.module)
> Sequential(
  (0): Linear(in_features=1, out_features=1, bias=True)
  (1): ReLU()
  (2): Linear(in_features=1, out_features=1, bias=True)
)