title: restsharp make multi async request
body: <p>it's easy to request an API with restsharp.org,
  but when i need to call two different API, first request holds code, and after response second one starts, i think it is not correct,
  below is my code:</p>
  
  <pre><code>var client = new RestClient("http://xxx.yyy.com/");
  
  var requestHotels = new RestRequest("api/hotelUi/home/hotelList", Method.POST);
  requestHotels.AddParameter("take", "16");                                               
  IRestResponse hotels = client.Execute(requestHotels); 
  List&lt;Hotel&gt; topHotels = JsonConvert.DeserializeObject&lt;List&lt;Hotel&gt;&gt;(hotels.Content); 
  
  var requestCities = new RestRequest("api/hotelUi/home/cityList", Method.POST);
  requestCities.AddParameter("take", "16");                                                 
  IRestResponse cities = client.Execute(requestCities);
  List&lt;City&gt; topCities = JsonConvert.DeserializeObject&lt;List&lt;City&gt;&gt;(cities.Content);    
  </code></pre>
  
  <p>as you see city request wait until hotel request response, but i think both of them must be send, and wait until both response come back.</p>
  
  <p>how can i do this like?</p>