code: def test_fi():
      # test identity of ma and ar representation of fi lag polynomial
      n = 100
      mafromar = arma_impulse_response(lpol_fiar(0.4, n=n), [1], n)
      assert_array_almost_equal(mafromar, lpol_fima(0.4, n=n), 13)
  
imports: from statsmodels.compat.pandas import QUARTER_END
  import datetime
  import numpy
  from numpy.testing import assert_, assert_allclose, assert_almost_equal, assert_array_almost_equal, assert_equal, assert_raises
  import pandas
  import pytest
  from statsmodels.sandbox.tsa.fftarma import ArmaFft
  from statsmodels.tsa.arima.model import ARIMA
  from statsmodels.tsa.arima_process import ArmaProcess, arma_acf, arma_acovf, arma_generate_sample, arma_impulse_response, index2lpol, lpol2index, lpol_fiar, lpol_fima
  from statsmodels.tsa.tests.results import results_arma_acf
  from statsmodels.tsa.tests.results.results_process import armarep
label_desc: Use image node_id 8 for calling a global function with example usage: test_fi() without return types