code: def test_decision_function(self, data):
      model = VWClassifier()
      model.fit(data.x, data.y)
      actual = model.decision_function(data.x)
      assert actual.shape[0] == 100
      assert np.isclose(actual[0], 0.4069, atol=1e-2)
  
imports: from collections import namedtuple
  import os
  import numpy
  from packaging import version
  import pandas
  import pytest
  from scipy.sparse import csr_matrix
  from sklearn import datasets, __version__
  from sklearn.model_selection import KFold
  from sklearn.utils.estimator_checks import check_estimator
  from vowpalwabbit.sklearn import VW, VWClassifier, VWRegressor, tovw, VWMultiClassifier, VWRegressor
label_desc: Use image node_id 1 for calling the TestVWClassifier obj's underlying member method code with example usage: obj.test_decision_function(data) without return types