append &rest lists ⇒ result
| list | each must be a proper list except the last, which may be any object. |
| result | an object. This will be a list unless the last list was not a list and all preceding lists were null. |
append returns a new list that is the concatenation of the copies. lists are left unchanged; the list structure of each of lists except the last is copied. The last argument is not copied; it becomes the cdr of the final dotted pair of the concatenation of the preceding lists, or is returned directly if there are no preceding non-empty lists.
(append '(a b c) '(d e f) '() '(g)) ⇒ (A B C D E F G)
(append '(a b c) 'd) ⇒ (A B C . D)
(setq lst '(a b c)) ⇒ (A B C)
(append lst '(d)) ⇒ (A B C D)
lst ⇒ (A B C)
(append) ⇒ NIL
(append 'a) ⇒ A