docs: def get_levels_of_description(self):
          """
          Returns an array of all levels of description defined in this Archivist's Toolkit instance.
          """
          if not hasattr(self, "levels_of_description"):
              cursor = self.db.cursor()
              levels = set()
              cursor.execute("SELECT distinct(resourceLevel) FROM Resources")
              for row in cursor:
                  levels.add(row)
              cursor.execute("SELECT distinct(resourceLevel) FROM ResourcesComponents")
              for row in cursor:
                  levels.add(row)
              self.levels_of_description = list(levels)
  
          return self.levels_of_description