gistfile1.cs

[Serializable]
public class Category
{
  public int Id { get; set; }
  public string Name { get; set; }
}
   
[Serializable]
public class User
{
  [Key]
  public string Email { get; set; }
}
   
[Serializable]
public class Task : IComparable<Task>
{
  public Guid Id { get; set; }
  public string Name { get; set; }
  public DateTime DueBy{ get; set; }
  public int CategoryId { get; set; }
   
  public int CompareTo(Task other)
  {
    return Id.CompareTo(other.Id);
  }
}