code: def typify(self, stack: Stack) -> List[Stack]:
          
  
          if len(stack.layers) == 1 and isinstance(stack.layers[0], lyr.Typing):
              return [stack]
  
          return [stack, Stack([lyr.Typing()])]
docs: Appends a typing stack after the given stack, but only if required
          (aka don't have two typing layers following each other).