code: func (r *SearchRequest) BatchedReduceSize(size int) *SearchRequest {
  	r.batchedReduceSize = &size
  	return r
  }
docs: // BatchedReduceSize specifies the number of shard results that should be
  // reduced at once on the coordinating node. This value should be used
  // as a protection mechanism to reduce the memory overhead per search request
  // if the potential number of shards in the request can be large.