code: def yl(self):
      return self.lower_bounds[..., 1]
  
imports: from __future__ import annotations
  from itertools import count
  from typing import Any, Callable, Dict, Optional, Tuple, Union
  import torch
  from botorch.exceptions import UnsupportedError
  from botorch.utils.probability.bvn import _bvnu_polar, _bvnu_taylor, bvn, bvnmom, bvnu, Phi
  from botorch.utils.testing import BotorchTestCase
  from torch import Tensor
label_desc: Use image node_id 5 for calling the TestBVN obj's underlying member method code with example usage: obj.yl() and returns: self