elisp - How to use add-to-list on a list returned by function -

i have function return list. may return blank list or number list. apply add-to-list return value. possible?

     (defun return-list () body....)      (setq test (add-to-list (return-list) 1) ) 

function add-to-list operates on variables, not lists. e.g.:

(defvar test (return-list)) (add-to-list 'test 1) 

if adding list unconditionally, use macro push operates on places:

(push 1 test) 

in case, however, can simpler:

(setq test (cons 1 (return-list))) 

if want add element if not there yet, use macro cl-pushnew operates on places too:

(pushnew 1 test) ;; `test' (1) (pushnew 1 test) ;; `test' still (1)