code: func ParseMetric(input string) (m labels.Labels, err error) {
  	p := newParser(input)
  	defer p.recover(&err)
  
  	m = p.metric()
  	if p.peek().typ != ItemEOF {
  		p.errorf("could not parse remaining input %.15q...", p.lex.input[p.lex.lastPos:])
  	}
  	return m, nil
  }
docs: // ParseMetric parses the input into a metric