docs: def _get_link(self, peer):
          """
          Returns a link to the given peer
  
          :return: A Link object
          :raise ValueError: Unknown peer
          """
          assert isinstance(peer, beans.Peer)
  
          # Look for a link to the peer, using routers
          for router in self._routers:
              link = router.get_link(peer)
              if link:
                  return link
  
          # Not found
          raise ValueError("No link to peer {0}".format(peer))