go.opentelemetry.io/otel/api/metric.MeterMust.NewInt64ValueObserver (method)

one use

	go.opentelemetry.io/otel/api/metric (current package)
		must.go#L98: func (mm MeterMust) NewInt64ValueObserver(name string, callback Int64ObserverFunc, oos ...InstrumentOption) Int64ValueObserver {