code: def test_compare_different_lengths(self):
      c1 = Categorical([], categories=["a", "b"])
      c2 = Categorical([], categories=["a"])
  
      msg = "Categoricals can only be compared if 'categories' are the same."
      with pytest.raises(TypeError, match=msg):
          c1 == c2
  
imports: import numpy
  import pytest
  import pandas
  from pandas import Categorical, DataFrame, Series, Timestamp, date_range
  import pandas._testing
label_desc: Use image node_id 13 for calling the TestCategoricalOps obj's underlying member method code with example usage: obj.test_compare_different_lengths() without return types