: gen.mkApply__(gen.mkRef(pos, primitives.BOX_UVALUE));
: gen.mkApply__(gen.mkGlobalRef(pos, primitives.BOX_UVALUE));
    private Tree transformUnit(int pos, Type pt) {        Tree unit = pt.isSameAs(UNBOXED_UNIT)            ? gen.mkUnitLit(pos)            : gen.mkApply__(gen.mkRef(pos, primitives.BOX_UVALUE));        return coerce(unit, pt);    }