3 (define (lookup key-1 key-2 table)
4 (let ((subtable (assoc key-1 (cdr table))))
6 (let ((record (assoc key-2 (cdr subtable))))
12 (define (insert! key-1 key-2 value table)
13 (let ((subtable (assoc key-1 (cdr table))))
15 (let ((record (assoc key-2 (cdr subtable))))
17 (set-cdr! record value)
19 (cons (cons key-2 value)