code: def test_dctn(self, xp, scp, dtype):
      fft_func = getattr(scp.fft, self.function)
      return self._run_transform(fft_func, xp, dtype)
  
file_path: cupy/tests/cupyx_tests/scipy_tests/fft_tests/test_realtransforms.py
imports: import numpy
  import pytest
  from cupyx.scipy import fft
  from cupy import testing
label_desc: Use image node_id 2 for calling the TestDctnDstn obj's underlying member method code with example usage: obj.test_dctn(xp, scp, dtype) and returns: self