deepSplice v -- yields a new list v where any members of v which are sequences are replaced by their elements, and so on.
Works also for sequences, and leaves other expressions unchanged. Copying the list v is always done when v is mutable.
i1 : deepSplice { (a,b,(c,d,(e,f))), g, h }
o1 = {a, b, c, d, e, f, g, h}
o1 : List