lsubst n new (LLazyApp fn args) = let args' = map (lsubst n new) args in
                                      LLazyApp fn args'
lsubst n new (LLazyApp fn args) = let args' = map (lsubst n new) args in
                                      LLazyApp fn args'
lsubst n new (LLazyApp fn args) = let args' = map (lsubst n new) args in
                                      LLazyApp fn args'