BetterHttpClient.ProxyManager.GetAvalibleProxy C# (CSharp) Метод

        public Proxy GetAvalibleProxy()
        {
            lock (_proxies)
            {
                Proxy selectedProxy = null;

                do
                {
                    if (_proxies.Count(t => t.IsOnline) == 0)
                        throw new AllProxiesBannedException();

                    selectedProxy = _proxies.FirstOrDefault(t => t.IsOnline && !t.IsBusy);
                    if (selectedProxy == null)
                    {
                        Thread.Sleep(35);
                    }

                } while (selectedProxy == null);

                selectedProxy.IsBusy = true;
                return selectedProxy;
            }
        }
        /// <summary>