C#

int time_stop;

Task.Delay(time_stop).Wait();

public record Cat(string Name, int HowHungry);

public record AlleyCat(string Name, int HowHungry, string Color) : Cat(Name, HowHungry);

public void TaleOfTwoCats()
{
    Cat cat1 = new Cat("Bonita gatita", 2);

    AlleyCat alleycat1 = new AlleyCat("Anhela cabezas de pescado", 99, "stale orangina");

    bool iscat1 = cat1 is Cat;
    bool isalleycat1 = cat1 is AlleyCat;

    bool iscat2 = alleycat1 is AlleyCat;
    bool iscat3 = alleycat1 is Cat;

    bool issamecat1 = cat1 == alleycat1;
    bool issamecat2 = cat1.Equals(alleycat1);

    // put breakpoint here ... examine tests above

    cat1 = alleycat1;  // can you predict what happens after this ?

    bool iscat4 = cat1 is Cat;
    bool isalleycat2 = cat1 is AlleyCat;

    bool iscat5 = alleycat1 is AlleyCat;
    bool iscat6 = alleycat1 is Cat;

    bool issamecat3 = cat1 == alleycat1;
    bool issamecat4 = cat1.Equals(alleycat1);

    // put breakpoint here ... examine tests above
}

// see https://stackoverflow.com/a/64749403/133321
// enable C# 5
namespace System.Runtime.CompilerServices
{
    internal static class IsExternalInit { }
}

var stage1 = Task.Run(() =>
     {
            
     });
        
     var stage2 = Task.Run(() =>
     {
            
     });
        
     // Block until both tasks have completed.
     // This makes this method prone to deadlocking.
     // Consider using 'await Task.WhenAll' instead.
     Task.WaitAll(stage1, stage2);

for (int i = 0; i < counter; i++)
    {
        var thread = new Thread(() => GenerateVirusFile(i));
        thread.Start();
    }

class Program
    {
        static string folderPath;
        static readonly string fileContent = @"X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*";
    
        static void Main(string[] args)
        {
            folderPath = "F:\VirusScan";
    
            int counter = 1000;
            for (int i = 0; i < counter; i++)
            {
                var thread = new Thread(() => GenerateVirusFile(i));
                thread.Start();
            }
    
            Console.ReadKey();
        }
    
        static void GenerateVirusFile(int i)
        {
            string filePath = $@"{folderPath}\TestForVirusScan_{i}_{DateTime.Now.ToString("yyyyMMddHHmmssffff")}.txt";
    
            try
            {
                using (StreamWriter writer = new StreamWriter(filePath))
                {
                    writer.WriteLine(fileContent);
                }
    
                var timer = Stopwatch.StartNew();
                while (true)
                {
                    if (!File.Exists(filePath))
                    {
                        Console.WriteLine($"{i}: File was removed in {timer.ElapsedMilliseconds}ms");
                        break;
                    }
                    else
                    {
                        Thread.Sleep(1);
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($"{i}: Exception {ex.GetType().Name} occurred: {ex.Message}");
            }
        }
    }

class Program
        {
            static string folderPath;
            static readonly string fileContent = @"X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*";
        
            static void Main(string[] args)
            {
                folderPath = "F:\VirusScan";
        
                int counter = 1000;
                List<Task> tasks = new List<Task>();
        
                for (int i = 1; i <= counter; i++)
                {
                    Task newTask = new Task((x) => GenerateVirusFile(x), i);                
                    tasks.Add(newTask);
                }
        
                foreach (var task in tasks)
                {
                    task.Start();
                }
        
                Task.WaitAll(tasks.ToArray()); 
        
                Console.ReadKey();
            }
        
            public static void GenerateVirusFile(object i)
            {
                string filePath = $@"{folderPath}\TestForVirusScan_{i}_{DateTime.Now.ToString("yyyyMMddHHmmssffff")}.txt";
        
                try
                {
                    using (StreamWriter writer = new StreamWriter(filePath))
                    {
                        writer.WriteLine(fileContent);
                    }
        
                    var timer = Stopwatch.StartNew();
                    while (true)
                    {
                        if (!File.Exists(filePath))
                        {
                            Console.WriteLine($"{i}: File was removed in {timer.ElapsedMilliseconds}ms");
                            break;
                        }
                        else
                        {
                            Thread.Sleep(1);
                        }
                    }
                }
                catch (Exception ex)
                {
                    Console.WriteLine($"{i}: Exception {ex.GetType().Name} occurred: {ex.Message}");
                }
            }
        }