code: def test_chi2_coo(coo_container):
      # Check that chi2 works with a COO matrix
      # (as returned by CountVectorizer, DictVectorizer)
      Xcoo = coo_container(X)
      mkchi2(k=2).fit_transform(Xcoo, y)
  
file_path: scikit-learn/sklearn/feature_selection/tests/test_chi2.py
imports: import warnings
  import numpy
  import pytest
  import scipy.stats
  from sklearn.feature_selection import SelectKBest, chi2
  from sklearn.feature_selection._univariate_selection import _chisquare
  from sklearn.utils._testing import assert_array_almost_equal, assert_array_equal
  from sklearn.utils.fixes import COO_CONTAINERS, CSR_CONTAINERS
label_desc: Use image node_id 3 for calling a global function with example usage: test_chi2_coo(coo_container) without return types