identity object → object

object — an object.

Returns its argument object.

(identity 101) → 101 
(mapcan #'identity (list (list 1 2 3) '(4 5 6))) → (1 2 3 4 5 6)

identity is intended for use with functions that require a function as an argument.

(eql x (identity x)) returns true for all possible values of x, but (eq x (identity x)) might return false when x is a number or character.

identity could be defined by

(defun identity (x) x)