title: How to use asynchronous TNetHTTPClient
body: <p>How to use asynchronous TNetHTTPClient?
  I tried following code, but it shows error.</p>
  <pre><code>procedure TForm1.Button1Click(Sender: TObject);
  var
    httpclient: TNetHTTPClient;
    output: string;
  begin
    httpclient := TNetHTTPClient.Create(nil);
    try
        httpclient.Asynchronous := True;
        output := httpclient.Get('https://google.com').ContentAsString;
    finally
      httpclient.Free;
    end;
  end;
  </code></pre>
  <p>Error:</p>
  <blockquote>
  <p>Error querying headers: The handle is in a wrong state for the requested operation</p>
  </blockquote>