assoc
(assoc key assoc_list)
The assoc function searches an association list assoc_list for key.
It returns the list entry if successful; otherwise, it returns nil.
: (setq product (list '(NAME "telephone") '(PRICE 149,00) '(COLOR "red"))) : (assoc 'name product)
(NAME "telephone")
: (assoc 'price product)
(PRICE 149,00)
: (assoc 'color product)
(COLOR "red")
: (assoc 'number product)
nil