* @since    3.10.0
	 * @version  3.10.0
	 */
	public function get_notification_subscription( $type, $trigger, $default = 'no' ) {

		$prefs = $this->get( 'notification_subscriptions' );
		if ( ! $prefs ) {
			$prefs = array();
		}

		if ( isset( $prefs[ $type ] ) && isset( $prefs[ $type ][ $trigger ] ) ) {
			return $prefs[ $type ][ $trigger ];
		}

		return $default;

	}

	/**
	 * Retrieve the student's overall grade
	 *
	 * Grade = sum of grades for all courses divided by number of enrolled courses
	 * if a course has no quizzes in it, it cannot be graded and is therefore excluded from the calculation.
	 *
	 * Cached data is automatically cleared when a student completes a quiz.
	 *
	 * @since 3.2.0
	 *
	 * @param boolean $use_cache If `false`, calculates the grade, otherwise utilizes cached data (if available)
	 * @return float|string Grade as float or "N/A"
	 */
	public function get_overall_grade( $use_cache = true ) {

		$grade = null;

		// Attempt to pull from the cache first.
		if ( $use_cache ) {

			$grade = $this->get( $this->meta_prefix . 'overall_grade' );

			if ( is_numeric( $grade ) ) {
				$grade = floatval( $grade );
			}
		}

		// Cache disabled or no cached data available.
		if ( ! $use_cache || null === $grade || '' === $grade ) {

			$grades = array();

			// Get courses.
			$courses = $this->get_courses(
				array(
					'limit' => 9999,
				)
			);

			// Loop through courses.