code: func (s *ChainService) ForAllPeers(closure func(sp *ServerPeer)) {
  	select {
  	case s.query <- forAllPeersMsg{closure: closure}:
  	case <-s.quit:
  	}
  }
docs: // ForAllPeers runs a closure over all peers (outbound and persistent) to which
  // the ChainService is connected. Nothing is returned because the peerState's
  // ForAllPeers method doesn't return anything as the closure passed to it
  // doesn't return anything.