public function is_enrollment_open() {

		// If no period is set, enrollment is automatically open.
		if ( 'yes' !== $this->get( 'enrollment_period' ) ) {

			$is_open = true;

		} else {

			$is_open = ( $this->has_date_passed( 'enrollment_start_date' ) && ! $this->has_date_passed( 'enrollment_end_date' ) );

		}

		/**
		 * Filters whether or not course enrollment is open.
		 *
		 * @since Unknown
		 *
		 * @param boolean     $is_open Whether or not enrollment is open.
		 * @param LLMS_Course $course  Course object.
		 */
		return apply_filters( 'llms_is_course_enrollment_open', $is_open, $this );
	}