a bug:

    i20 : a = (x,y)

    o20 = (x, y)

    o20 : Sequence

    i21 : (b,c) = a

    o21 = (x, y)

    o21 : Sequence

    i22 : b

    o22 = x

    o22 : Symbol

    i23 : a = 1:x

    o23 = 1 : (x)

    o23 : Sequence

    i24 : (b) = a

    o24 = 1 : (x)

    o24 : Sequence

    i25 : a

    o25 = 1 : (x)			-- wanted to get x here

    o25 : Sequence
