code: func (api *API) ShardNodes(ctx context.Context, indexName string, shard uint64) ([]*Node, error) {
  	span, _ := tracing.StartSpanFromContext(ctx, "API.ShardNodes")
  	defer span.Finish()
  
  	if err := api.validate(apiShardNodes); err != nil {
  		return nil, errors.Wrap(err, "validating api method")
  	}
  
  	return api.cluster.shardNodes(indexName, shard), nil
  }
docs: // ShardNodes returns the node and all replicas which should contain a shard's data.