code: func (c *PodConfig) Channel(source string) chan<- interface{} {
  	c.sourcesLock.Lock()
  	defer c.sourcesLock.Unlock()
  	c.sources.Insert(source)
  	return c.mux.Channel(source)
  }
docs: // Channel creates or returns a config source channel.  The channel
  // only accepts PodUpdates