code: def test_meta_classifier_not_none():
      X = np.random.rand(100, 2)
      y = np.random.randint(0, 2, 100)
      meta = METADES(meta_classifier=GaussianNB())
      meta.fit(X, y)
      check_is_fitted(meta.meta_classifier_, "classes_")
      assert isinstance(meta.meta_classifier_, GaussianNB)
  
imports: from unittest.mock import MagicMock
  import numpy
  import pytest
  from sklearn.linear_model import Perceptron
  from sklearn.naive_bayes import GaussianNB
  from sklearn.svm import SVC
  from sklearn.utils.estimator_checks import check_estimator
  from sklearn.utils.validation import check_is_fitted
  from deslib.des.meta_des import METADES
label_desc: Use image node_id 3 for calling a global function with example usage: test_meta_classifier_not_none() without return types