code: func metricUnits(m string) (unit string, base string, ok bool) {
  	ss := strings.Split(m, "_")
  
  	for _, u := range baseUnits {
  		// Also check for "no prefix".
  		for _, p := range append(unitPrefixes, "") {
  			for _, s := range ss {
  				// Attempt to explicitly match a known unit with a known prefix,
  				// as some words may look like "units" when matching suffix.
  				//
  				// As an example, "thermometers" should not match "meters", but
  				// "kilometers" should.
  				if s == p+u {
  					return p + u, u, true
  				}
  			}
  		}
  	}
  
  	return "", "", false
  }
docs: // metricUnits attempts to detect known unit types used as part of a metric name,
  // e.g. "foo_bytes_total" or "bar_baz_milligrams".