pkg/textparse/promparse.go
func (p *PromParser) Series() ([]byte, *int64, float64) {
	if p.hasTS {
		return p.series, &p.ts, p.val
	}
	return p.series, nil, p.val
}
func (p *PromParser) Series() ([]byte, *int64, float64) {
	if p.hasTS {
		return p.series, &p.ts, p.val
	}
	return p.series, nil, p.val
}
// Series returns the bytes of the series, the timestamp if set, and the value
// of the current sample.