Ion Auth - Restrict emails when registering

gistfile1.txt

                //MODEL
		class users_m()
		{
		    function restrict_email()
		    {
		    	$emails = array('test@test.com', 'test2@test2.com');
		        $this->db->where_in($emails);
		    }
		}


                //CONTROLLER
                function register_user()
                {
		    //set the hook
		    $this->ion_auth->set_hook('pre_register', 'restrict_emails', $this->users_m, 'restrict_email');

		    //other stuff...

                    $user = array(
                        'email' => $this->input->post('email'),
                        'password' => $this->input->post('password'),
                        ...
                    );

		    //before the user is created the hook will be called automatically
		    $this->ion_auth->register(...
                }