Recognizer for association lists
(alistp x) is true if and only if x is a list of cons pairs.
(alistp x) has a guard of t.
Function: alistp
(defun alistp (l) (declare (xargs :guard t)) (cond ((atom l) (eq l nil)) (t (and (consp (car l)) (alistp (cdr l))))))
