code: def test_inverse_train_data_fill_zero(lags, index_type):
      y = y_airline
      if index_type == "int":
          y = y.reset_index(drop=True)
      diff = Differencer(lags).fit(y)
      result = diff.inverse_transform(diff.transform(y))
      _assert_array_almost_equal(result, y)
  
file_path: sktime/sktime/transformations/series/tests/test_differencer.py
imports: import numpy
  import pandas
  import pytest
  from sktime.datasets import load_airline
  from sktime.transformations.series.difference import Differencer
  from sktime.utils._testing.estimator_checks import _assert_array_almost_equal
  from sktime.utils.validation._dependencies import _check_soft_dependencies
label_desc: Use image node_id 6 for calling a global function with example usage: test_inverse_train_data_fill_zero(lags, index_type) without return types