public NewUser Add(
            string name,
            string email,
            DateTime dateOfBirth)
        {
            var newUser = new NewUser(
                name,
                email,
                dateOfBirth)
            {
                Id = Guid.NewGuid()
            };

            _userDictionary.Add(newUser.Email, newUser);
            var userAddedEventArgs = new UserAddedEventArgs {
                User = newUser
            };

            OnUserAdded(userAddedEventArgs);

            return(newUser);
        }
 protected virtual void OnUserAdded(UserAddedEventArgs e)
 {
     UserAdded?.Invoke(this, e);
 }