code: func (s *Store) Coordinate(node string, ws memdb.WatchSet) (uint64, lib.CoordinateSet, error) {
  	tx := s.db.Txn(false)
  	defer tx.Abort()
  
  	tableIdx := maxIndexTxn(tx, "coordinates")
  
  	iter, err := tx.Get("coordinates", "node", node)
  	if err != nil {
  		return 0, nil, fmt.Errorf("failed coordinate lookup: %s", err)
  	}
  	ws.Add(iter.WatchCh())
  
  	results := make(lib.CoordinateSet)
  	for raw := iter.Next(); raw != nil; raw = iter.Next() {
  		coord := raw.(*structs.Coordinate)
  		results[coord.Segment] = coord.Coord
  	}
  	return tableIdx, results, nil
  }
docs: // Coordinate returns a map of coordinates for the given node, indexed by
  // network segment.