Return a new |ChartPart| instance added to *package* containing
        a chart of *chart_type* and depicting *chart_data*.

def new(cls, chart_type, chart_data, package):
        """
        Return a new |ChartPart| instance added to *package* containing
        a chart of *chart_type* and depicting *chart_data*.
        """
        chart_blob = chart_data.xml_bytes(chart_type)
        partname = package.next_partname(cls.partname_template)
        content_type = CT.DML_CHART
        chart_part = cls.load(partname, content_type, chart_blob, package)
        xlsx_blob = chart_data.xlsx_blob
        chart_part.chart_workbook.update_from_xlsx_blob(xlsx_blob)
        return chart_part