gossip.go
func newGossipSenders(sender protocolSender, stop <-chan struct{}) *gossipSenders {
	return &gossipSenders{
		sender:  sender,
		stop:    stop,
		senders: make(map[string]*gossipSender),
	}
}
func newGossipSenders(sender protocolSender, stop <-chan struct{}) *gossipSenders {
	return &gossipSenders{
		sender:  sender,
		stop:    stop,
		senders: make(map[string]*gossipSender),
	}
}
// NewGossipSenders returns a usable GossipSenders leveraging the ProtocolSender.
// TODO(pb): is stop chan the best way to do that?