code: def test_tabulate(self):
      empty = ConditionalFreqDist()
      self.assertEqual(empty.conditions(), [])
      with pytest.raises(ValueError):
          empty.tabulate(
              conditions="BUG"
          )  # nonexistent keys shouldn't be added
      self.assertEqual(empty.conditions(), [])
  
file_path: nltk/nltk/test/unit/test_cfd_mutation.py
imports: import unittest
  import pytest
  from nltk import ConditionalFreqDist, tokenize
label_desc: Use image node_id 1 for calling the TestEmptyCondFreq obj's underlying member method code with example usage: obj.test_tabulate() without return types