Implement till 4.38

util.scm

@@ -7,6 +7,17 @@
       (display b)))
   (newline))
 
+; I have this here to avoid name-conflicts with the amb implementation in
+; amb.scm.
+(define (my-assert a b)
+  (cond ((equal? a b) (display "[ok]"))
+    (else
+      (display "[error] ")
+      (display a)
+      (display " != ")
+      (display b)))
+  (newline))
+
 (define (gcd a b)
   (if (= b 0) (abs a) (gcd b (remainder a b))))