func (r *Reporter) Discrete(name string, tags []string, val float64) error {
	metric := fmt.Sprintf("%s|%s:val=%v", name, strings.Join(tags, ","), val)
	r.metrics = append(r.metrics, metric)
	return nil
}
func (r *Reporter) Discrete(name string, tags []string, val float64) error {
	metric := fmt.Sprintf("%s|%s:val=%v", name, strings.Join(tags, ","), val)
	r.metrics = append(r.metrics, metric)
	return nil
}
// Discrete implements instruments.Reporter