def pop(db):
            limit = 2 # <- Not empirically/theoretically tested
            db.execute("SELECT value FROM queue ORDER BY rowid LIMIT (?)", (limit,))
            value = db.fetchall() # a list of (value, ) tuples, or None
            if value:
                # pop values (i.e. delete rows with len(value) lowest row ids)
                db.execute("DELETE FROM queue WHERE rowid in (SELECT rowid FROM queue ORDER BY rowid LIMIT (?))",
                           (len(value),))

            return value