fix tests

@@ -38,27 +38,27 @@ let bal = (l, x, d, r) => {
 }
 if hl > hr + 2 {
 switch l {
-| Empty => assert false
+| Empty => assert(false)
 | Node(ll, lv, ld, lr, _) =>
 if height(ll) >= height(lr) {
 create(ll, lv, ld, create(lr, x, d, r))
 } else {
 switch lr {
-| Empty => assert false
+| Empty => assert(false)
 | Node(lrl, lrv, lrd, lrr, _) =>
 create(create(ll, lv, ld, lrl), lrv, lrd, create(lrr, x, d, r))
 }
 }
 }
 } else if hr > hl + 2 {
 switch r {
-| Empty => assert false
+| Empty => assert(false)
 | Node(rl, rv, rd, rr, _) =>
 if height(rr) >= height(rl) {
 create(create(l, x, d, rl), rv, rd, rr)
 } else {
 switch rl {
-| Empty => assert false
+| Empty => assert(false)
 | Node(rll, rlv, rld, rlr, _) =>
 create(create(l, x, d, rll), rlv, rld, create(rlr, rv, rd, rr))
 }