code: def test_ci():
      """Test confidence intervals."""
      # isolated test of CI functions
      arr = np.linspace(0, 1, 1000)[..., np.newaxis]
      assert_allclose(
          _ci(arr, method="parametric"),
          _ci(arr, method="bootstrap"),
          rtol=0.005,
      )
      assert_allclose(
          bootstrap_confidence_interval(
              arr, stat_fun="median", random_state=0
          ),
          bootstrap_confidence_interval(
              arr, stat_fun="mean", random_state=0
          ),
          rtol=0.1,
      )
  
file_path: mne-python/mne/stats/tests/test_permutations.py
imports: import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_equal
  from scipy import sparse, stats
  from mne.stats import permutation_cluster_1samp_test
  from mne.stats.permutations import _ci, bootstrap_confidence_interval, permutation_t_test
label_desc: Use image node_id 3 for calling a global function with example usage: test_ci() without return types