MACRO: shadowing-boa ( class -- tuple )
    [
        all-slots [ name>> ] map
        [
            reverse! sets:members [ length ] keep 
            [ narray reverse! ] dip
            [ swap 2array ] 2map
        ] keep
    ] keep
    [
        initial-values reverse!
        [ 2array ] 2map
        [
            '[
                [ first ] [ last ] bi
                _ swap '[ drop _ ] change-at
            ] each
        ] keep
        reverse! [ last ] each
    ] keep boa ;