code: func NewBroadcaster(buflen int) Broadcaster {
  	b := &broadcaster{
  		input:   make(chan interface{}, buflen),
  		reg:     make(chan chan<- interface{}),
  		unreg:   make(chan chan<- interface{}),
  		outputs: make(map[chan<- interface{}]bool),
  	}
  
  	go b.run()
  
  	return b
  }
docs: // NewBroadcaster creates a new broadcaster with the given input
  // channel buffer length.