code: def new(cls, chart_type, chart_data, package):
          
          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
docs: Return a new |ChartPart| instance added to *package* containing
          a chart of *chart_type* and depicting *chart_data*.