code: public static Response executeAndWait(Request request) {
          List<Response> responses = executeBatchAndWait(request);
  
          if (responses == null || responses.size() != 1) {
              throw new FacebookException("invalid state: expected a single response");
          }
  
          return responses.get(0);
      }
docs: Executes a single request on the current thread and returns the response.
  <p/>
  This should only be used if you have transitioned off the UI thread.
  
  @param request
  the Request to execute
  
  @return the Response object representing the results of the request
  
  @throws FacebookException
  If there was an error in the protocol used to communicate with the service