Thanks, i understand.
One more question, if forward function look like this:
   def forward(self,x):
        out = self.layer1(x)
        out = nn.Flatten()(out)

And sequential container look like this:
nn.Sequential(layer[0] + [nn.Flatten()])

or like this:
nn.Sequential( [nn.Flatten()] + layer[0])

Which one is right ?
I mean, I have problems with the order of using the functional APIs in  nn.Sequential