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