assembly in c#

using System;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Windows.Forms;
using CommonSnappableTypes;

namespace MyExtendableApp
{
    class Program
    {
        [STAThread]
        static void Main(string[] args)
        {
            Console.WriteLine("***** Welcome to MyTypeViewer *****");
            do
            {
                Console.WriteLine("\nWould you like to load a snapin? [Y,N]");

                // Get name of type.
                string answer = Console.ReadLine();

                // Does user want to quit?
                if (!answer.Equals("Y", StringComparison.OrdinalIgnoreCase))
                {
                    break;
                }

                // Try to display type.
                try
                {
                    LoadSnapin();
                }
                catch (Exception ex)
                {
                    Console.WriteLine("Sorry, can't find snapin");
                }
            } while (true);
        }

        static void LoadSnapin()
        {
            // Allow user to select an assembly to load.
            OpenFileDialog dlg = new OpenFileDialog
            {
                //set the initial directory to the path of this project
                InitialDirectory = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location),
                Filter = "assemblies (*.dll)|*.dll|All files (*.*)|*.*",
                FilterIndex = 1
            };

            if (dlg.ShowDialog() != DialogResult.OK)
            {
                Console.WriteLine("User cancelled out of the open file dialog.");
                return;
            }
            if (dlg.FileName.Contains("CommonSnappableTypes"))
                Console.WriteLine("CommonSnappableTypes has no snap-ins!");
            else if (!LoadExternalModule(dlg.FileName))
                Console.WriteLine("Nothing implements IAppFunctionality!");
        }

        private static bool LoadExternalModule(string path)
        {
            bool foundSnapIn = false;
            Assembly theSnapInAsm = null;

            try
            {
                // Dynamically load the selected assembly.
                theSnapInAsm = Assembly.LoadFrom(path);
            }
            catch (Exception ex)
            {
                Console.WriteLine($"An error occurred loading the snapin: {ex.Message}");
                return foundSnapIn;
            }

            Type[] theTypes = theSnapInAsm.GetTypes();

            for (int i = 0; i < theTypes.Length; i++) {
                Type t;
                t = theTypes[i].GetInterface("ISortAndPrint");
                if (t != null) {
                    foundSnapIn = true;
                    object o = theSnapInAsm.CreateInstance(theTypes[i].FullName);
                    loaded = o as ISortAndPrint;
                }
            }
            // Get all IAppFunctionality compatible classes in assembly.
            /*var theClassTypes = from t in theSnapInAsm.GetTypes()
                where t.IsClass && (t.GetInterface("IAppFunctionality") != null)
                select t;
                */
            // Now, create the object and call DoIt() method.
            foreach (Type t in theClassTypes)
            {
                foundSnapIn = true;
                // Use late binding to create the type.
                IAppFunctionality itfApp = (IAppFunctionality) theSnapInAsm.CreateInstance(t.FullName, true);
                itfApp?.DoIt();
                //lstLoadedSnapIns.Items.Add(t.FullName);

            }
            return foundSnapIn;
        }

    }
}