code: func (n *Network) PeerPort(p *Peer, portName PortName) uint16 {
  	peerPorts := n.PortsByPeerID[p.ID()]
  	Expect(peerPorts).NotTo(BeNil())
  	return peerPorts[portName]
  }
docs: // PeerPort returns the named port reserved for the Peer instance.