code: func New(ctx context.Context, s storage.Store, c *ast.Compiler, txn storage.Transaction) (w *Watcher, err error) {
  	w = create(ctx, s, c)
  	w.trigger, err = s.Register(ctx, txn, storage.TriggerConfig{OnCommit: w.notify})
  	return w, err
  }
docs: // New creates and returns a new Watcher on the store using the compiler provided.
  // Once a compiler is provided to create a Watcher, it must not be modified, or else
  // the results produced by the Watcher are undefined.