docs: def GetClientVersion(client_id, token=None):
    """Returns last known GRR version that the client used."""
    if data_store.RelationalDBEnabled():
      sinfo = data_store.REL_DB.ReadClientStartupInfo(client_id=client_id)
      if sinfo is not None:
        return sinfo.client_info.client_version
      else:
        return config.CONFIG["Source.version_numeric"]
    else:
      with aff4.FACTORY.Open(client_id, token=token) as client:
        cinfo = client.Get(client.Schema.CLIENT_INFO)
        if cinfo is not None:
          return cinfo.client_version
        else:
          return config.CONFIG["Source.version_numeric"]