Fix bug found in project 04

Project-02-03-04/triplaprograms/homework.tripla

@@ -0,0 +1,16 @@
+let f(x, y) {
+    if (x == 0) then
+        let g(x, z) {
+            x * y + z
+        } in g(2 * y, x)
+    else
+        x + 1
+    }
+    g (a, i) {
+        while (i > 0) do {
+            a = a * f(a, i);
+            i = i - 1
+        };
+        a + 42
+    }
+in f (1, 2); g(3, 3)