title: How to add Pie chart in hole of Donut chart in Flutter, I tried with Stack widget but it's working for text only
body: <p>I am trying to fill the hole of donut chart with pie chart in Flutter for my project but unable to do so.</p>
  
  <pre><code>                             Expanded(
                               child:Stack(
                                children:&lt;Widget&gt;[
                               charts.PieChart(
                                 _seriesPieData1,
                              animate: true,
                              animationDuration: Duration(milliseconds: 500),
                              selectionModels: [
                                new charts.SelectionModelConfig(
                                  type: charts.SelectionModelType.info,
                                ),
                              ],
                                 defaultRenderer: new charts.ArcRendererConfig(arcWidth: 25),
                               ),
                                 Center
                                  (
                                   child: charts.PieChart(
                                     _seriesPieData,
                                     animate: true,
                                     animationDuration: Duration(milliseconds: 500),
                                     selectionModels: [
                                       new charts.SelectionModelConfig(
                                         type: charts.SelectionModelType.info,
                                       ),
                                     ],
                                       defaultRenderer: new charts.ArcRendererConfig(arcRendererDecorators: [
                                         new charts.ArcLabelDecorator(
                                             labelPosition: charts.ArcLabelPosition.inside)
                                       ],),
                                   ),
                                 ),
                              ],
                                 ),
                            ),
  </code></pre>