async getNewsletterSubscriberStats(options = {}) {
        // Extract newsletter_id from options
        const {newsletter_id: newsletterId, ...otherOptions} = options;
        
        // If no newsletterId is provided, we can't get specific stats
        if (!newsletterId) {
            return {data: [{total: 0, deltas: []}]};
        }
        
        const result = await this.posts.getNewsletterSubscriberStats(newsletterId, otherOptions);
        return result;
    }
Get newsletter subscriber statistics including total count and daily deltas

@param {Object} options
@param {string} [options.newsletter_id] - ID of the specific newsletter to get stats for
@param {string} [options.date_from] - Start date filter in YYYY-MM-DD format
@param {string} [options.date_to] - End date filter in YYYY-MM-DD format
@returns {Promise<{data: Object}>}