Members::set_user_invited( int $user_id, int $form_id )

	protected function set_user_invited( $user_id, $form_id ) {
		if ( $this->is_user_invited( $user_id, $form_id ) ) {
			return;
		}

		$meta_key = $this->module->manager()->get_prefix() . 'invited_users';

		$this->module->manager()->forms()->add_meta( $form_id, $meta_key, $user_id );
	}