code: func (s QueryTiming) SpanOperation() string {
  	switch s {
  	case EvalTotalTime:
  		return "promqlEval"
  	case ResultSortTime:
  		return "promqlSort"
  	case QueryPreparationTime:
  		return "promqlPrepare"
  	case InnerEvalTime:
  		return "promqlInnerEval"
  	case ExecQueueTime:
  		return "promqlExecQueue"
  	case ExecTotalTime:
  		return "promqlExec"
  	default:
  		return "Unknown query timing"
  	}
  }
docs: // Return a string representation of a QueryTiming span operation.