delays := retry.Delays[1*time.Second, 2*time.Second, 4*time.Second]
result, err := retry.DoR(ctx, delays, func(ctx context.Context) (int, error) {
    return 0, errors.New("")
})

err := retry.Do(ctx, retry.Exponential(time.Second, 1.5, 0.5), func(ctx context.Context) (int, error) {
    return 0, errors.New("")
})

result, err := retry.DoR(ctx, retry.TruncatedExponential(time.Second, 1.5, 0, 10*time.Second), func(ctx context.Context) (int, error) {
    return 0, errors.New("")
})

result, err := retry.DoR(ctx, retry.Constant(time.Second), func(ctx context.Context) (int, error) {
    result, err := DoSomething()
    switch {
    case errors.Is(err, ErrInvalidArguments)  
        return retry.Permanent(err) // Prevent retrying.  
    default:
        return err
    }
    return result, nil
})