code: func (f *Factory) Namespace(scope metrics.NSOptions) metrics.Factory {
  	newFactory := &Factory{
  		factories: make([]metrics.Factory, len(f.factories)),
  	}
  	for i, factory := range f.factories {
  		newFactory.factories[i] = factory.Namespace(scope)
  	}
  	return newFactory
  }
docs: // Namespace implements metrics.Factory interface