Its not like that.
The codes that I posted allow the user to select as many as they want then you need after that to iterate the selection set and do your stuff at each entity object.
e.g:
(if (setq ss (ssget '((0 . "*POLYLINE") (8 . "DWG_SHEET") (-4 . "<AND") (-4 . "&=") (70 . 1) (-4 . "AND>"))))
(repeat (setq i (sslength ss))
(setq ent (ssname ss (setq i (1- i)))) ;; one entity which is eaual to single selection like, (car (entsel "\nSelect object :"))
;; do your stuff here ....
)
)