code: func (r *Store) WithConfig(ctx context.Context, name string) context.Context {
  	name = strings.TrimSuffix(name, "/")
  	mp := r.MountPoint(name)
  	if _, found := r.mounts[mp]; found {
  		return r.cfg.Mounts[mp].WithContext(ctx)
  	}
  	return r.cfg.Root.WithContext(ctx)
  }
docs: // WithConfig populates the context with the substore config