code: def within_geo_box(self, key, southwest, northeast):
          
          self._add_condition(key, '$within', {'$box': [southwest, northeast]})
          return self
docs: 增加查询条件，限制返回结果指定字段值的位置在指定坐标范围之内。
  
          :param key: 查询条件字段名
          :param southwest: 限制范围西南角坐标
          :param northeast: 限制范围东北角坐标
          :rtype: Query