code: func legendLabels(rpt *Report) []string {
  	prof := rpt.prof
  	o := rpt.options
  	var label []string
  	if len(prof.Mapping) > 0 {
  		if prof.Mapping[0].File != "" {
  			label = append(label, "File: "+filepath.Base(prof.Mapping[0].File))
  		}
  		if prof.Mapping[0].BuildID != "" {
  			label = append(label, "Build ID: "+prof.Mapping[0].BuildID)
  		}
  	}
  	if o.SampleType != "" {
  		label = append(label, "Type: "+o.SampleType)
  	}
  	if prof.TimeNanos != 0 {
  		const layout = "Jan 2, 2006 at 3:04pm (MST)"
  		label = append(label, "Time: "+time.Unix(0, prof.TimeNanos).Format(layout))
  	}
  	if prof.DurationNanos != 0 {
  		label = append(label, fmt.Sprintf("Duration: %v", time.Duration(prof.DurationNanos)))
  	}
  	return label
  }
docs: // legendLabels generates labels exclusive to graph visualization.