add one more test

examples/acceptance_tests/059/lib/tests.ak

@@ -5,3 +5,13 @@ test foo() {
     _ -> False
   }
 }
+
+test sort_by_1() {
+  let xs = [[4, 3], [2, 3]]
+  let g = when xs is {
+    [[x, xs2], [y, ys2]] -> True
+    _ -> False
+  }
+
+  g == True
+}