✅ Covariance & Contravariance

    public interface IRepository<T>
    {
        T Get();
        void Add(T item);
    }

    public class Animal
    {
        public string Name { get; set; }
    }

    public class Dog : Animal
    {
        public string Breed { get; set; }
    }

    public class AnimalRepository : IRepository<Animal>
    {
        public Animal Get()
        {
            Console.WriteLine("Getting an animal from the repository.");
            return new Animal { Name = "Fido" };
        }

        public void Add(Animal item)
        {
            Console.WriteLine("Adding an animal to the repository.");
        }
    }
    public class DogRepository : IRepository<Dog>
    {
        public Dog Get()
        {
            Console.WriteLine("Getting a dog from the repository.");
            return new Dog { Name = "Buddy", Breed = "Golden Retriever" };
        }

        public void Add(Dog item)
        {
            Console.WriteLine("Adding a dog to the repository.");
        }
    }

    internal class Program
    {
        public static void UseAnimalRepository(IRepository<Animal> repository)
        {
            var animal = repository.Get();
            Console.WriteLine("Used repository to get an animal: " + animal.Name);
            repository.Add(new Animal { Name = "Spot" });
            Console.WriteLine("Used repository to add an animal.");
        }

        public static void Main()
        {
            AnimalRepository animalRepository = new AnimalRepository();
            DogRepository dogRepository = new DogRepository();

            Console.WriteLine("Using Animal Repository:");
            UseAnimalRepository(animalRepository);

            Console.WriteLine("\nUsing Dog Repository:");
            UseAnimalRepository(dogRepository); // This line won't work without contravariance
        }
    }

    public interface IRepository<T>
    {
        T Get();
        void Add(T item);
    }

    public class Animal
    {
        public string Name { get; set; }
    }

    public class Dog : Animal
    {
        public string Breed { get; set; }
    }

    public class AnimalRepository : IRepository<Animal>
    {
        public Animal Get()
        {
            Console.WriteLine("Getting an animal from the repository.");
            return new Animal { Name = "Fido" };
        }

        public void Add(Animal item)
        {
            Console.WriteLine("Adding an animal to the repository.");
        }
    }
    public class DogRepository : IRepository<Dog>
    {
        public Dog Get()
        {
            Console.WriteLine("Getting a dog from the repository.");
            return new Dog { Name = "Buddy", Breed = "Golden Retriever" };
        }

        public void Add(Dog item)
        {
            Console.WriteLine("Adding a dog to the repository.");
        }
    }

    internal class Program
    {
        public static void UseAnimalRepository(IRepository<Animal> repository)
        {
            var animal = repository.Get();
            Console.WriteLine("Used repository to get an animal: " + animal.Name);
            repository.Add(new Animal { Name = "Spot" });
            Console.WriteLine("Used repository to add an animal.");
        }

        public static void Main()
        {
            AnimalRepository animalRepository = new AnimalRepository();
            DogRepository dogRepository = new DogRepository();

            Console.WriteLine("Using Animal Repository:");
            UseAnimalRepository(animalRepository);

            Console.WriteLine("\nUsing Dog Repository:");
            UseAnimalRepository(dogRepository); // This line won't work without contravariance
        }
    }