code: def switch_to_aux_top_layer(self):
          
          if self.aux_top_layer is None:
              raise RuntimeError("Empty auxiliary top layer in the network.")
          saved_top_layer = self.top_layer
          saved_top_size = self.top_size
          self.top_layer = self.aux_top_layer
          self.top_size = self.aux_top_size
          yield
          self.aux_top_layer = self.top_layer
          self.aux_top_size = self.top_size
          self.top_layer = saved_top_layer
          self.top_size = saved_top_size
docs: Context that construct cnn in the auxiliary arm.