class Delegator {
    public generic delegate = none

    public function operation {
        if (typeof(delegate) == "none") {
            return "default implementation"
        }
        return delegate()
    }
}

function thing {
    return "delegate implementation"
}

// default, no delegate
var d = new Delegator()
println (d.operation())

// delegate
var d1 = new Delegator()
d1.delegate = thing
println (d1.operation())