remove rubbish

Author: OneAdder

src/nf/nf_layer_submodule.f90

@@ -123,10 +123,6 @@ pure module subroutine backward_3d(self, previous, gradient)
         select type(prev_layer => previous % p)
           type is(input3d_layer)
             call this_layer % backward(prev_layer % output, gradient)
-!          type is(dense_layer)
-!            call this_layer % forward(prev_layer % output)
-!          type is(flatten_layer)
-!            call this_layer % backward(prev_layer % output, gradient)
         end select
 
     end select