func ProvideRoundTripperDurationHistogram(o prometheus.HistogramOpts, l *ClientLabellers) fx.Annotated {
    return fx.Annotated{
        Name: o.Name,
        Target: func(f xmetrics.Factory) (RoundTripperDuration, error) {
            h, err := f.NewHistogramVec(o, l.LabelNames())