code: def test_idct_definition(fftwdata_size, rdt, type):
      xr, yr, dt = fftw_dct_ref(type, fftwdata_size, rdt)
      x = idct(yr, type=type)
      dec = dec_map[(idct, rdt, type)]
      assert_equal(x.dtype, dt)
      assert_allclose(x, xr, rtol=0.0, atol=np.max(xr) * 10 ** (-dec))
  
imports: from os.path import join, dirname
  from typing import Callable, Dict, Tuple, Union, Type
  import numpy
  from numpy.testing import assert_array_almost_equal, assert_equal, assert_allclose
  import pytest
  from pytest import raises
  from scipy.fft._pocketfft.realtransforms import dct, idct, dst, idst, dctn, idctn, dstn, idstn
label_desc: Use image node_id 18 for calling a global function with example usage: test_idct_definition(fftwdata_size, rdt, type) without return types