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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def areaBetween(requestContext, *seriesLists):
 """ Draws the vertical area in between the two series in seriesList. Useful for visualizing a range such as the minimum and maximum latency for a service. areaBetween expects **exactly one argument** that results in exactly two series (see example below). The order of the lower and higher values series does not matter. The visualization only works when used in conjunction with ``areaMode=stacked``. Most likely use case is to provide a band within which another metric should move. In such case applying an ``alpha()``, as in the second example, gives best visual results. Example:: &target=areaBetween(service.latency.{min,max})&areaMode=stacked &target=alpha(areaBetween(service.latency.{min,max}),0.3)&areaMode=stacked If for instance, you need to build a seriesList, you should use the ``group`` function, like so:: &target=areaBetween(group(minSeries(a.*.min),maxSeries(a.*.max))) """

    if len(seriesLists) == 1:
        [seriesLists] = seriesLists
    assert len(seriesLists) == 2, ("areaBetween series argument must "
                                   "reference *exactly* 2 series")
    lower, upper = seriesLists
    if len(lower) == 1:
        [lower] = lower
    if len(upper) == 1:
        [upper] = upper
    lower.options['stacked'] = True
    lower.options['invisible'] = True

    upper.options['stacked'] = True
    lower.name = upper.name = "areaBetween(%s)" % upper.pathExpression
    return [lower, upper]