code: func (m *metricCollectorRegistry) Register(initMetricCollector func(string) MetricCollector) {
  	m.lock.Lock()
  	defer m.lock.Unlock()
  
  	m.registry = append(m.registry, initMetricCollector)
  }
docs: // Register places a MetricCollector Initializer in the registry maintained by this metricCollectorRegistry.