code: func (p *OpenMetricsParser) Unit() ([]byte, []byte) {
  	// The Prometheus format does not have units.
  	return p.l.b[p.offsets[0]:p.offsets[1]], p.text
  }
docs: // Unit returns the metric name and unit in the current entry.
  // Must only be called after Next returned a unit entry.
  // The returned byte slices become invalid after the next call to Next.