Please help - easy

I'm sure this is pretty simple and seeing as how I have'nt LISP'ed for a few years. How do I modifiy the following:

;;; Inserting CopeNote
(DEFUN C:CN ()
(save_sysvars)
(set_layer "text")
(hunt_block "copenote")
(COMMAND ".INSERT" block_dwg PAUSE (wm_scale) "" "")
(restore_sysvars)
)

I want to add before the ' (set_layer "text") ' to check and see if a layer 'text2' exists if so then set that, else (set_layer "text")