def Run(self, max_age=60 * 60 * 24 * 7):
    counts = {}
    self.fields.append("count")
    self.results = []
    for client in self._QueryResults(max_age):
      version = client.get("GRR client")
      try:
        counts[version] += 1
      except KeyError:
        counts[version] = 1
    for version, count in counts.iteritems():
      self.results.append({"GRR client": version, "count": count})
    self.SortResults("count")
Run the report.
dataset/ETHPy150Open google/grr/grr/lib/aff4_objects/reports.py/VersionBreakdownReport.Run