perfdata.go
func RenderPerfdata(perfdata []PerfDatum) string {
	value := ""
	if len(perfdata) == 0 {
		return value
	}
	// Demarcate start of perfdata in check output.
	value += " |"
	for _, datum := range perfdata {
		value += fmt.Sprintf(" %v", datum)
	}
	return value
}
func RenderPerfdata(perfdata []PerfDatum) string {
	value := ""
	if len(perfdata) == 0 {
		return value
	}
	// Demarcate start of perfdata in check output.
	value += " |"
	for _, datum := range perfdata {
		value += fmt.Sprintf(" %v", datum)
	}
	return value
}
// RenderPerfdata accepts a slice of PerfDatum objects and returns their
// concatenated string representations in a form suitable to append to
// the first line of check output.