code: def test_densetransformer():
      data = np.array([[1, 2, 3], [4, 5, 6]])
      X = csr_matrix(data)
      X_t = preprocessing.DenseTransformer().fit_transform(X)
      assert isinstance(X_t, np.ndarray)
  
file_path: sk-dist/skdist/tests/test_preprocessing.py
label_desc: Use image node_id 6 for calling a global function with example usage: test_densetransformer() without return types