[].
      c := [4,23,6];
      a := [ op(c), op(c)];
[[4,3],[2,8]] est également du type
listlist.
      evalb({op(c),op(c)} = {op(c)})  -> true
union, intersect ou minus.
     COLORS[bleu] := {bleu, blue, blau};
     COLORS[rouge] := {rouge, red, rot};
     print(COLORS)
        table([
             bleu  = {bleu, blue, blau},
             rouge = {rouge, red, rot}
              ]);
     for c in entries(COLORS) do print(c) od;