code: def test_is_fitted(self):
      cat = CatBoostAlgorithm(self.params)
      self.assertFalse(cat.is_fitted())
      cat.fit(self.X, self.y)
      self.assertTrue(cat.is_fitted())
  
imports: import unittest
  import tempfile
  import json
  import copy
  import numpy
  import pandas
  import os
  from numpy.testing import assert_almost_equal
  from sklearn import datasets
  from supervised.algorithms.catboost import CatBoostAlgorithm, additional
  from supervised.utils.metric import Metric
  import tempfile
label_desc: Use image node_id 7 for calling the CatBoostAlgorithmTest obj's underlying member method code with example usage: obj.test_is_fitted() without return types