js.execute.ignore=true
====
>>> main.whiley
function f(int x, int y) -> int:
   return x ** y
   
public export method test():
   assume f(2,-1) == 2
---
E713 main.whiley 2,15
E730 main.whiley 2,15
====
>>> main.whiley 5:6
   assume f(2,1) == 2
   assume f(2,2) == 4
---
E730 main.whiley 2,15
=====
>>> main.whiley 1:2
function f(int x, int y) -> int
requires y >= 0:
---