/// <summary>
        /// Removes instances from the load balancer. Once the instance is deregistered, it will stop receiving traffic from the load balancer.
        /// </summary>
        /// <param name="loadBalancer">The name associated with the load balancer.</param>
        /// <param name="instances">A list of instance IDs that should be deregistered with the load balancer.</param>
        /// <param name="settings">The <see cref="LoadBalancingSettings"/> used during the request to AWS.</param>
        /// <param name="cancellationToken">A cancellation token that can be used by other objects or threads to receive notice of cancellation.</param>
        public async Task <bool> DeregisterInstances(string loadBalancer, IList <string> instances, LoadBalancingSettings settings, CancellationToken cancellationToken = default(CancellationToken))
        {
            if (String.IsNullOrEmpty(loadBalancer))
            {
                throw new ArgumentNullException("loadBalancer");
            }
            if ((instances == null) || (instances.Count == 0))
            {
                throw new ArgumentNullException("instances");
            }



            //Create Request
            AmazonElasticLoadBalancingClient           client  = this.CreateClient(settings);
            DeregisterInstancesFromLoadBalancerRequest request = new DeregisterInstancesFromLoadBalancerRequest();

            request.LoadBalancerName = loadBalancer;

            foreach (string instance in instances)
            {
                request.Instances.Add(new Instance(instance));
            }



            //Check Response
            DeregisterInstancesFromLoadBalancerResponse response = await client.DeregisterInstancesFromLoadBalancerAsync(request, cancellationToken);

            if (response.HttpStatusCode == HttpStatusCode.OK)
            {
                _Log.Verbose("Successfully deregistered instances '{0}'", string.Join(",", instances));
                return(true);
            }
            else
            {
                _Log.Error("Failed to deregister instances '{0}'", string.Join(",", instances));
                return(false);
            }
        }