code: func (s *Store) Coordinates(ws memdb.WatchSet) (uint64, structs.Coordinates, error) {
  	tx := s.db.Txn(false)
  	defer tx.Abort()
  
  	// Get the table index.
  	idx := maxIndexTxn(tx, "coordinates")
  
  	// Pull all the coordinates.
  	iter, err := tx.Get("coordinates", "id")
  	if err != nil {
  		return 0, nil, fmt.Errorf("failed coordinate lookup: %s", err)
  	}
  	ws.Add(iter.WatchCh())
  
  	var results structs.Coordinates
  	for coord := iter.Next(); coord != nil; coord = iter.Next() {
  		results = append(results, coord.(*structs.Coordinate))
  	}
  	return idx, results, nil
  }
docs: // Coordinates queries for all nodes with coordinates.