S9 LIB  (assp procedure^2 object alist)  ==>  object | #f

Find the first member X of an alist for which

      (procedure^2 object (car X))

holds. When no such member exists, return #F.

(assp char=? #\b '((#\a . 1) (#\b . 2)))  ==>  (#\b . 2)
