public static ApplicationUser AuthenticateUser(PivotIdentity pivotIdentity)
        {
            authenticatedUser = new ApplicationUser
            {
                Id = pivotIdentity.Sub,
                Email = pivotIdentity.Email,
                Gender = pivotIdentity.Gender,
                Birthdate = pivotIdentity.Birthdate,
                Firstname = pivotIdentity.Given_name,
                Lastname = pivotIdentity.Family_name
            };

            return authenticatedUser;
        }
 public static void SignOut()
 {
     authenticatedUser = null;
 }