def numslice(x, start=None, stop=None, system=10):
    if start is None:
        start = 0
    if stop is None:
        stop = int(mlog.log(system)(x)) + 1

    if start < 0 and stop >= 0:
        start = int(mlog.log(system)(x)) + 1 + start
    elif stop < 0 and start >= 0:
        stop = int(mlog.log(system)(x)) + 1 + stop

    if stop <= start:
        raise ValueError

    return nth(x, stop - 1, abs(start - stop), system)