code: def test_irfftn(self):
      x = random((30, 20, 10))
      assert_array_almost_equal(x, fft.irfftn(fft.rfftn(x)))
      for norm in ["backward", "ortho", "forward"]:
          assert_array_almost_equal(
              x, fft.irfftn(fft.rfftn(x, norm=norm), norm=norm)
          )
  
imports: import queue
  import threading
  import multiprocessing
  import numpy
  import pytest
  from numpy.random import random
  from numpy.testing import assert_array_almost_equal, assert_array_equal, assert_allclose
  from pytest import raises
  import scipy.fft
label_desc: Use image node_id 13 for calling the TestFFT1D obj's underlying member method code with example usage: obj.test_irfftn() without return types