(assoc-keyword key l) is (keyword-value-listp l).
keyword-value-listp
Major Section: PROGRAMMING
If l is a list of even length of the form (k1 a1 k2 a2 ... kn an),
where each ki is a keyword, then (assoc-keyword key l) is the
first tail of l starting with key if key is some ki, and is
nil otherwise.
The guard for (assoc-keyword key l) is (keyword-value-listp l).