code: def insert_chart(self, chart_type, chart_data):
          
          rId = self.part.add_chart_part(chart_type, chart_data)
          graphicFrame = self._new_chart_graphicFrame(
              rId, self.left, self.top, self.width, self.height
          )
          self._replace_placeholder_with(graphicFrame)
          return PlaceholderGraphicFrame(graphicFrame, self._parent)
docs: Return a |PlaceholderGraphicFrame| object containing a new chart of
          *chart_type* depicting *chart_data* and having the same position and
          size as this placeholder. *chart_type* is one of the
          :ref:`XlChartType` enumeration values. *chart_data* is a |ChartData|
          object populated with the categories and series values for the chart.
          Note that the new |Chart| object is not returned directly. The chart
          object may be accessed using the
          :attr:`~.PlaceholderGraphicFrame.chart` property of the returned
          |PlaceholderGraphicFrame| object.