code: def _detect_available_configs():
          
          with channels_lock:
              available_channels = list(channels.keys())
  
          # find a currently unused channel
          get_extra = lambda: "channel-{}".format(randint(0, 9999))
          extra = get_extra()
          while extra in available_channels:
              extra = get_extra()
  
          available_channels += [extra]
  
          return [
              {'interface': 'virtual', 'channel': channel}
              for channel in available_channels
          ]
docs: Returns all currently used channels as well as
          one other currently unused channel.
  
          .. note::
  
              This method will run into problems if thousands of
              autodetected busses are used at once.