code: func (q MatchAllQuery) Source() (interface{}, error) {
  	// {
  	//   "match_all" : { ... }
  	// }
  	source := make(map[string]interface{})
  	params := make(map[string]interface{})
  	source["match_all"] = params
  	if q.boost != nil {
  		params["boost"] = *q.boost
  	}
  	if q.queryName != "" {
  		params["_name"] = q.queryName
  	}
  	return source, nil
  }
docs: // Source returns JSON for the match all query.