assoc KEY LIST function returns the first element of an
alist whose car is equal to
Is there a built-in Emacs Lisp function which returns all elements of the
alist whose cars are equal to
KEY, as a sub-alist, or list of values? After all, there is no requirement that an
alist have unique keys.
(assoc foo '((foo . 5) (bar . 6) (foo . 7))) = '(foo . 5)
(assoc-all foo '((foo . 5) (bar . 6) (foo . 7))) = '((foo . 5) (foo . 7))