code: func MustInit(cfg *config.Config, registry ...*prometheus.Registry) {
  	if !cfg.PrometheusMetricsEnabled {
  		return
  	}
  	var registryToUse *prometheus.Registry
  	if len(registry) > 0 {
  		registryToUse = registry[0]
  	} else {
  		registryToUse = prometheus.DefaultRegisterer.(*prometheus.Registry)
  	}
  	MetricsEngineGlobal = NewMetricsEngine(cfg, registryToUse)
  	MetricsEngineGlobal.collection = true
  }
docs: // Initializes the Global MetricsEngine used throughout Agent
  // Currently, we use the Prometheus Global Default Registerer, which also collecs
  // basic Go application metrics that we use (like memory usage).
  // In future cases, we can use a custom Prometheus Registry to group metrics.
  // For unit testing purposes, we only focus on API calls and use our own Registry