perfdata.go
func isThresholdSet(t *float64) bool {
	switch {
	case t == nil:
		return false
	case math.IsInf(*t, 0):
		return false
	case math.IsNaN(*t):
		return false
	}
	return true
}
func isThresholdSet(t *float64) bool {
	switch {
	case t == nil:
		return false
	case math.IsInf(*t, 0):
		return false
	case math.IsNaN(*t):
		return false
	}
	return true
}
// isThresholdSet returns true if one of min, max, warn or crit are set
// and false otherwise. They are determined to be 'set' if they are not
// a) the nil pointer, b) infinity (positive or negative) or c) NaN.