code: func (r *BulkUpdateRequest) Script(script *Script) *BulkUpdateRequest {
  	r.script = script
  	r.source = nil
  	return r
  }
docs: // Script specifies an update script.
  // See https://www.elastic.co/guide/en/elasticsearch/reference/7.0/docs-bulk.html#bulk-update
  // and https://www.elastic.co/guide/en/elasticsearch/reference/7.0/modules-scripting.html
  // for details.