code: func (r *PCPRegistry) AddMetricByString(str string, val interface{}, t MetricType, s MetricSemantics, u MetricUnit) (Metric, error) {
  	metric, indom, instances, err := parseString(str)
  	if err != nil {
  		return nil, err
  	}
  
  	if instances == nil {
  		return r.addSingletonMetricByString(metric, val, t, s, u)
  	}
  
  	return r.addInstanceMetricByString(metric, val, indom, instances, t, s, u)
  }
docs: // AddMetricByString dynamically creates a PCPMetric