/// <summary>
        /// Updates a <see cref="ConvertKitSubscriber"/>.
        /// </summary>
        /// <param name="subscriber">The subscriber.</param>
        /// <returns>The updated subscriber.</returns>
        public async Task<ConvertKitSubscriber> UpdateAsync(long subscriberId, ConvertKitSubscriber subscriber)
        {
            var req = RequestEngine.CreateRequest($"subscribers/{subscriberId}", Method.PUT, "subscriber");

            return await RequestEngine.ExecuteRequestAsync<ConvertKitSubscriber>(_RestClient, req);
        }
        /// <summary>
        /// Updates a <see cref="ConvertKitSubscriber"/>.
        /// </summary>
        /// <param name="subscriber">The subscriber.</param>
        /// <returns>The updated subscriber.</returns>
        public async Task <ConvertKitSubscriber> UpdateAsync(long subscriberId, ConvertKitSubscriber subscriber)
        {
            var req = RequestEngine.CreateRequest($"subscribers/{subscriberId}", Method.PUT, "subscriber");

            return(await RequestEngine.ExecuteRequestAsync <ConvertKitSubscriber>(_RestClient, req));
        }