original.name="Function_Valid_25"
======
>>> main.whiley
type Handler is { function handler(int)->int }
type nHandler is null | Handler

function instanceof(nHandler attr) -> bool:
    if attr is Handler:
        return true
    else:
        return false

function id(int x) -> (int y):
    return x

public export method test():
    assume instanceof(null) == false
    assume instanceof({handler: &id}) == true
---