old way of implementing built-in methods

gistfile1.java

public static class EqualRange extends SuMethod2 {
    { params = new FunctionSpec(array("value", "block"), Boolean.FALSE); }
    @Override
    public Object eval2(Object self, Object a, Object b) {
        Range r = ((SuContainer) self).equalRange(a, b);
        return SuContainer.of(r.left, r.right);
    }
}