original.name="TypeEquals_Valid_48"
======
>>> main.whiley
function f(int|null x) -> (int r):
//
if !(x is int && x >= 0):
return 0
else:
return x
public export method test():
assume f(-1) == 0
assume f(0) == 0
assume f(1) == 1
assume f(2) == 2
assume f(null) == 0
---