(defun _atom (a) (and a (atom a)))
(setq
a nil
b 'a
c 1
d 'c
lst '(1 2 3)
ss (ssget "_X")
)
; (boundp 'a) => nil
; (boundp 'b) => T
; (boundp 'c) => T
; (boundp 'd) => T
; (boundp 'lst) => T
; (boundp 'ss) => T
; (boundp a) => nil
; (boundp b) => nil
; (boundp c) => nil
; (boundp d) => T
; (boundp lst) => nil
; (boundp ss) => nil
; (_atom a) => nil
; (_atom b) => T
; (_atom c) => T
; (_atom d) => T
; (_atom lst) => nil
; (_atom ss) => T