title: How to get message sender (author) of telegram channel using TLSharp
body: <p>I have a c# program that using <code>TLSharp</code> library to extract data from a Telegram channel. I want to get sender id of each post but I'm getting null when I try to retrieve <code>FromID</code> value of each <code>TLMessage</code> object. Here is my key part of code:</p>
  
  <pre><code>// Get Channel Messages
  var history = await client.GetHistoryAsync(target, 0, -1, 100) as TLChannelMessages;
  
  // Show Message Sender Id For Each Message
  foreach (var message in history.Messages.OfType&lt;TLMessage&gt;())
  {
      MessageBox.Show(message.FromId.Value.ToString());
  }
  </code></pre>
  
  <p>Unfortunately <code>message.FromId</code> is <code>Null</code> in every foreach iteration.
  I need this program so much please help me! </p>