public static function create_lesson( $course_id, $section_id, $title = '', $excerpt = '' ) {

		// No course id or section id? no new lesson!.
		if ( ! isset( $course_id ) || ! isset( $course_id ) ) {
			return;
		}

		// Set the lesson_order variable.
		// Get the count of lessons in the section.
		$section      = new LLMS_Section( $section_id );
		$lesson_order = $section->get_next_available_lesson_order();

		$title = isset( $title ) ? $title : 'New Lesson';

		$post_id = self::create( 'lesson', $title, $excerpt );

		// If post created set parent section, parent course and order determined above.
		if ( $post_id ) {
			update_post_meta( $post_id, '_llms_order', $lesson_order );

			$lesson                 = new LLMS_Lesson( $post_id );
			$updated_parent_section = $lesson->set_parent_section( $section_id );
			$updated_parent_course  = $lesson->set_parent_course( $course_id );

		}

		return $post_id;
	}