code: func (r *Reporter) Metric(name string, tags []string, v float32) {
  	r.metrics = append(r.metrics, Metric{
  		Name:   name,
  		Points: [][2]interface{}{[2]interface{}{r.timestamp, v}},
  		Tags:   tags,
  		Host:   r.Hostname,
  	})
  }
docs: // Metric appends a new metric to the reporter. The value v must be either an
  // int64 or float64, otherwise an error is returned