code: def test_exception_if_unseen_gets_not_permitted_value(errors):
      with pytest.raises(ValueError):
          CountFrequencyEncoder(unseen=errors)
  
imports: import warnings
  import numpy
  import pandas
  import pytest
  from numpy import nan
  from feature_engine.encoding import CountFrequencyEncoder
label_desc: Use image node_id 15 for calling a global function with example usage: test_exception_if_unseen_gets_not_permitted_value(errors) without return types