public override async Task <IdentityResult> AddToRoleAsync(string userId, string role)
        {
            var result = await base.AddToRoleAsync(userId, role);

            if (result.Succeeded)
            {
                if (role == "Teacher")
                {
                    await UserStore.AddTeacherInfo(userId, new TeacherInfo());
                }
                else if (role == "Student")
                {
                    await UserStore.AddStudentInfo(userId, new StudentInfo());
                }
                return(IdentityResult.Success);
            }
            return(result);
        }