code: def test_enforce_index_freq(item, freq):
      """Tests that enforce freq infers the right frequency."""
      item = _enforce_index_freq(item)
      assert item.index.freq == freq
  
imports: import numpy
  import pandas
  import pytest
  from sktime.datatypes import MTYPE_REGISTER, SCITYPE_REGISTER
  from sktime.datatypes._check import AMBIGUOUS_MTYPES, check_is_mtype
  from sktime.datatypes._examples import get_examples
  from sktime.datatypes._vectorize import VectorizedDF, _enforce_index_freq
  from sktime.utils._testing.deep_equals import deep_equals
  from sktime.utils.pandas import df_map
  from sktime.utils.parallel import _get_parallel_test_fixtures
label_desc: Use image node_id 12 for calling a global function with example usage: test_enforce_index_freq(item, freq) without return types