Solved by Nikronic in post #2 
              
              
                Hi, 
It is similar to nn.Module in PyTorch. You can combine your classes however you want to creating a class that derives nn.Module. Here is example: 
class Combined(nn.Module):
    def __init__(self, model1, model2):
        super(Combined, self).__init__()
        self.first_model=model1
        …