FILE: main.kt
    public final fun R|Y|.test(): R|kotlin/String?| {
        lval a: R|kotlin/Int| = when (this@R|/test|) {
            ($subj$ is R|F|) ->  {
                Int(1)
            }
            ($subj$ is R|G|) ->  {
                Int(2)
            }
            else ->  {
                ^test Null(null)
            }
        }

        ^test Null(null)
    }