public void Save(Contact entity)
 {
     _contacts.Add(entity);
 }
 public void Update(Contact entity, Guid id)
 {
     var contact = _contacts.FirstOrDefault(x => x.Id == id);
     contact.Email = entity.Email;
     contact.Name = entity.Name;
 }
 public void Delete(Contact entity)
 {
     _contacts.Remove(entity);
 }