code: def channels(self):
          
  
          # from ProgramConfigElement()
          if hasattr(self, "pce_channels"):
              return self.pce_channels
  
          conf = getattr(
              self, "extensionChannelConfiguration", self.channelConfiguration)
  
          if conf == 1:
              if self.psPresentFlag == -1:
                  return 0
              elif self.psPresentFlag == 1:
                  return 2
              else:
                  return 1
          elif conf == 7:
              return 8
          elif conf > 7:
              return 0
          else:
              return conf
docs: channel count or 0 for unknown