code: def test_process_multiplication(self):
      process1 = ArmaProcess.from_coeffs([0.9])
      process2 = ArmaProcess.from_coeffs([0.7])
      process3 = process1 * process2
      assert_equal(process3.arcoefs, np.array([1.6, -0.7 * 0.9]))
      assert_equal(process3.macoefs, np.array([]))
  
      process1 = ArmaProcess.from_coeffs([0.9], [0.2])
      process2 = ArmaProcess.from_coeffs([0.7])
      process3 = process1 * process2
  
      assert_equal(process3.arcoefs, np.array([1.6, -0.7 * 0.9]))
      assert_equal(process3.macoefs, np.array([0.2]))
  
      process1 = ArmaProcess.from_coeffs([0.9], [0.2])
      process2 = process1 * (np.array([1.0, -0.7]), np.array([1.0]))
      assert_equal(process2.arcoefs, np.array([1.6, -0.7 * 0.9]))
  
      assert_raises(TypeError, process1.__mul__, [3])
  
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 4 for calling the TestArmaProcess obj's underlying member method code with example usage: obj.test_process_multiplication() without return types