code: def test_conf_int_bca_scaler(bs_setup):
      num_bootstrap = 100
      bs = IIDBootstrap(bs_setup.y)
  
      ci = bs.conf_int(np.mean, reps=num_bootstrap, method="bca")
      msg = (
          "conf_int(method='bca') scalar input regression. Ensure "
          "output is at least 1D with numpy.atleast_1d()."
      )
      assert ci.shape == (2, 1), msg
  
imports: from __future__ import annotations
  import copy
  from typing import Callable, NamedTuple
  import warnings
  import numpy
  from numpy.random import RandomState
  from numpy.testing import assert_allclose, assert_equal
  import pandas
  from pandas.testing import assert_frame_equal, assert_series_equal
  import pytest
  import scipy.stats
  from arch.bootstrap import CircularBlockBootstrap, IIDBootstrap, IndependentSamplesBootstrap, MovingBlockBootstrap, StationaryBootstrap
  from arch.bootstrap._samplers_python import stationary_bootstrap_sample
  from arch.bootstrap._samplers_python import stationary_bootstrap_sample_python
  from arch.bootstrap.base import _loo_jackknife
  from arch.utility.exceptions import StudentizationError
label_desc: Use image node_id 14 for calling a global function with example usage: test_conf_int_bca_scaler(bs_setup) without return types