Add new Example.

Author: mohammadKarimi

Examples/NotificationService.cs Examples/E1/NotificationService.csExamples/NotificationService.cs renamed to Examples/E1/NotificationService.cs

@@ -0,0 +1,40 @@
+public interface INotification
+{
+    void Send(string message);
+}
+
+public class EmailNotification : INotification
+{
+    public void Send(string message) => Console.WriteLine($"Email sent: {message}");
+}
+
+public class SmsNotification : INotification
+{
+    public void Send(string message) => Console.WriteLine($"SMS sent: {message}");
+}
+
+#region Thid block of code is not in your code base, it is a library(3rd party)
+public class SlackNotification
+{
+    public void PostMessageToChannel(string channel, string message)
+    {
+        Console.WriteLine($"Message sent to Slack channel {channel}: {message}");
+    }
+} 
+#endregion
+
+public class NotificationService()
+{
+    public ... Get(string type)
+    {
+        if (type == "Email")
+            return new ...();
+        else if (type == "SMS")
+            return new ...();
+        else if (type == "Slack")
+            return new ...();
+
+        else
+            throw new ArgumentException("Invalid notification type.");
+    }
+}