title: WebClient does not contain the definition for SendCommandAsync()
body: <p>I'm trying to change the light color according to the temperature. I can obtain the temperature value, but I can't change the color basing on its value. </p>
  
  <p>I am using this code.</p>
  
  <pre><code>private async void button6_Click_1(object sender, EventArgs e) {
      string weburl = "http://api.openweathermap.org/data/2.5/weather?q=" + textBox1.Text + "&amp;mode=xml&amp;units";
      var client = new System.Net.WebClient();
      var xml = await new WebClient().DownloadStringTaskAsync(new Uri(weburl));
  
      XmlDocument doc = new XmlDocument();
      doc.LoadXml(xml);
      string szTemp = doc.DocumentElement.SelectSingleNode("temperature").Attributes["value"].Value;
      double temp = (double.Parse(szTemp) - 32) * 5 / 9;              
      label1.Text = temp.ToString("N1") + " Celcius"; 
      double degree = temp;
  
      if (degree &gt;= 20 &amp;&amp; degree &lt;30)
      {
          MessageBox.Show("hot");
          var command = new LightCommand();
          command.TurnOn().SetColor("000000");
          command.Brightness = 128;
          var result = await client.SendCommandAsync(command);
      }
  }
  </code></pre>
  
  <p>When I debug it, it gives me the following error.</p>
  
  <blockquote>
    <p>WebClient does not contain a definition for 'SendCommandAsync' and no extension method 'SendCommandAsync' accepting a first argument of type 'WebClient' could not be found(are you missing a using directive or an assembly reference?)</p>
  </blockquote>
  
  <p>How I can solve this error?</p>
  
  <p>Under the button 6 code, can I make another button (let's say button 7) which changes color to red, and make this button 7 execute automatically when the temperature is greater than 20 degree Celsius?  </p>