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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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