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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 __remove_category(self, id):
 """move all activities to unsorted and remove category"""


        affected_query = """
            SELECT id
              FROM facts
             WHERE activity_id in (SELECT id FROM activities where category_id=?)
        """
        affected_ids = [res[0] for res in self.fetchall(affected_query, (id,))]

        update = "update activities set category_id = -1 where category_id = ?"
        self.execute(update, (id, ))

        self.execute("delete from categories where id = ?", (id, ))

        self.__remove_index(affected_ids)