code: def _list_bundle(self):
      return {
          os.path.join(
              pth.data_path(["bundle", d], environ=self.environ)
          )
          for d in os.listdir(
              pth.data_path(["bundle"], environ=self.environ),
          )
      }
  
imports: import os
  from nose_parameterized import parameterized
  import pandas
  import sqlalchemy
  from toolz import valmap
  import toolz.curried.operator
  from trading_calendars import TradingCalendar, get_calendar
  from zipline.assets import ASSET_DB_VERSION
  from zipline.assets.asset_writer import check_version_info
  from zipline.assets.synthetic import make_simple_equity_info
  from zipline.data.bundles import UnknownBundle, from_bundle_ingest_dirname, ingestions_for_bundle
  from zipline.data.bundles.core import _make_bundle_core, BadClean, to_bundle_ingest_dirname, asset_db_path
  from zipline.lib.adjustment import Float64Multiply
  from zipline.pipeline.loaders.synthetic import make_bar_data, expected_bar_values_2d
  from zipline.testing import subtest, str_to_seconds
  from zipline.testing.fixtures import WithInstanceTmpDir, ZiplineTestCase, WithDefaultDateBounds
  from zipline.testing.predicates import assert_equal, assert_false, assert_in, assert_is, assert_is_instance, assert_is_none, assert_raises, assert_true
  from zipline.utils.cache import dataframe_cache
  from zipline.utils.functional import apply
  import zipline.utils.paths
label_desc: Use image node_id 10 for calling the BundleCoreTestCase obj's underlying member method code with example usage: obj._list_bundle() and returns: unknown