def _differentiate_line_chart_type(cls, plot):
        lineChart = plot._element

        def has_line_markers():
            matches = lineChart.xpath('c:ser/c:marker/c:symbol[@val="none"]')
            if matches:
                return False
            return True

        if has_line_markers():
            return {
                ST_Grouping.STANDARD: XL.LINE_MARKERS,
                ST_Grouping.STACKED: XL.LINE_MARKERS_STACKED,
                ST_Grouping.PERCENT_STACKED: XL.LINE_MARKERS_STACKED_100,
            }[plot._element.grouping_val]
        else:
            return {
                ST_Grouping.STANDARD: XL.LINE,
                ST_Grouping.STACKED: XL.LINE_STACKED,
                ST_Grouping.PERCENT_STACKED: XL.LINE_STACKED_100,
            }[plot._element.grouping_val]