js.execute.ignore=true
=====
>>> main.whiley
method f(int[] ls, int x) -> bool
requires |ls| >= 1:
    return all { i in x..1 | i < 0 || ls[i] >= 0 }

public export method test():
   bool r1 = f([1,2],0)
   assume r1
   bool r2 = f([1],0)
   assume r2
   bool r3 = f([1],-1)
   assume r3
   bool r4 = f([1],2)
---
E710 main.whiley 3,22:25
E727 main.whiley 3,22:25
=====
>>> main.whiley 2:2
requires x < 1
---
E700 main.whiley 13,13:20
E716 main.whiley 13,13:20
=====
>>> main.whiley 14:15
---