code: def _get_bucket(self):
      return oss2.Bucket(
          auth=oss2.Auth(
              access_key_id=self._access_key_id,
              access_key_secret=self._access_key_secret,
          ),
          endpoint=self._end_point,
          bucket_name=self._bucket_name,
      )
  
file_path: mars/mars/lib/filesystem/_oss_lib/handle.py
imports: from io import IOBase
  from ....utils import lazy_import
  from .common import parse_osspath, oss_stat
label_desc: Use image node_id 4 for calling the OSSIOBase obj's underlying member method code with example usage: obj._get_bucket() and returns: oss2