def _differentiate_bubble_chart_type(cls, plot):
        def first_bubble3D(bubbleChart):
            results = bubbleChart.xpath("c:ser/c:bubble3D")
            return results[0] if results else None

        bubbleChart = plot._element
        bubble3D = first_bubble3D(bubbleChart)

        if bubble3D is None:
            return XL.BUBBLE
        if bubble3D.val:
            return XL.BUBBLE_THREE_D_EFFECT
        return XL.BUBBLE