lispdoc  results for rassoc 
(rassoc item alist &key key (test nil testp) (testnot nil notp))  Function: Return the cons in ALIST whose CDR is equal (by a given test or EQL) to the ITEM.

Example:(defun handlespecialfloat (code name) (aif (rassoc code *specialfloats*) (car it) (storeerror "~A Cannot be represented." name)))  Mentioned in: CLtL2  15.6. Association Lists HyperSpec  Function RASSOC, RASSOCIF, RASSOCIFNOT PCL  lookup tables alists and plists 
(rassocif predicate alist &key key)  Function: Return the first cons in ALIST whose CDR satisfies PREDICATE. If KEY is supplied, apply it to the CDR of each cons before testing.

Mentioned in: CLtL2  15.6. Association Lists HyperSpec  Function RASSOC, RASSOCIF, RASSOCIFNOT PCL  lookup tables alists and plists  
(rassocifnot predicate alist &key key)  Function: Return the first cons in ALIST whose CDR does not satisfy PREDICATE. If KEY is supplied, apply it to the CDR of each cons before testing.

Mentioned in: CLtL2  15.6. Association Lists HyperSpec  Function RASSOC, RASSOCIF, RASSOCIFNOT PCL  lookup tables alists and plists  
(alexandria.0.dev:rassocvalue alist key &key (test 'eql))  Function: RASSOCVALUE is an alist accessor very much like RASSOC, but it can be used with SETF.

By Bill Moorier 