*       # Encode RLE
        define('rle(str)c,n') :(rle_end)
rle     str len(1) . c :f(return)
        str span(c) @n =
        rle = rle n c :(rle)
rle_end

*       # Decode RLE
        define('elr(str)c,n') :(elr_end)
elr     str span('0123456789') . n len(1) . c = :f(return)
        elr = elr dupl(c,n) :(elr)
elr_end

*       # Test and display
        str = 'WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW'
        output = str;
        str = rle(str); output = str
        str = elr(str); output = str
end