docs: def GetReportData(self, get_report_args, token):
      """Filter the last week of user actions."""
      ret = rdf_report_plugins.ApiReportData(
          representation_type=RepresentationType.STACK_CHART)
  
      week_duration = rdfvalue.Duration("7d")
      num_weeks = math.ceil(get_report_args.duration.seconds /
                            week_duration.seconds)
      weeks = range(0, num_weeks)
      start_time = get_report_args.start_time
      end_time = start_time + num_weeks * week_duration
      user_activity = collections.defaultdict(lambda: {week: 0 for week in weeks})
  
      entries = self._LoadUserActivity(
          start_time=get_report_args.start_time, end_time=end_time, token=token)
  
      for username, timestamp, count in entries:
        week = (timestamp - start_time).seconds // week_duration.seconds
        if week in user_activity[username]:
          user_activity[username][week] += count
  
      user_activity = sorted(iteritems(user_activity))
      user_activity = [(user, data)
                       for user, data in user_activity
                       if user not in aff4_users.GRRUser.SYSTEM_USERS]
  
      ret.stack_chart.data = [
          rdf_report_plugins.ApiReportDataSeries2D(
              label=user,
              points=(rdf_report_plugins.ApiReportDataPoint2D(x=x, y=y)
                      for x, y in sorted(data.items())))
          for user, data in user_activity
      ]
  
      return ret