code: func (item *MultiGetItem) Version(version int64) *MultiGetItem {
  	item.version = &version
  	return item
  }
docs: // Version can be MatchAny (-3), MatchAnyPre120 (0), NotFound (-1),
  // or NotSet (-2). These are specified in org.elasticsearch.common.lucene.uid.Versions.
  // The default in Elasticsearch is MatchAny (-3).