code: def GetReportData(self, get_report_args, token):
      
      report = rdf_report_plugins.ApiReportData(
          representation_type=rdf_report_plugins.ApiReportData.RepresentationType
          .PIE_CHART)
  
      graph_series = client_report_utils.FetchMostRecentGraphSeries(
          get_report_args.client_label,
          rdf_stats.ClientGraphSeries.ReportType.OS_TYPE,
          token=token)
      if graph_series is not None:
        for graph in graph_series.graphs:
          # Find the correct graph and merge the OS categories together
          if "%s day" % self.__class__.ACTIVE_DAYS in graph.title:
            for sample in graph:
              report.pie_chart.data.Append(
                  rdf_report_plugins.ApiReportDataPoint1D(
                      label=sample.label, x=sample.y_value))
            break
  
      report.pie_chart.data = sorted(
          report.pie_chart.data, key=lambda point: point.label)
  
      return report
docs: Extract only the operating system type from the active histogram.