code: def test_psd(self):
      freqs = self.freqs_density
      spec, fsp = mlab.psd(
          x=self.y,
          NFFT=self.NFFT_density,
          Fs=self.Fs,
          noverlap=self.nover_density,
          pad_to=self.pad_to_density,
          sides=self.sides,
      )
      assert spec.shape == freqs.shape
      self.check_freqs(spec, freqs, fsp, self.fstims)
  
imports: from numpy.testing import assert_allclose, assert_almost_equal, assert_array_equal, assert_array_almost_equal_nulp
  import numpy
  import pytest
  from matplotlib import mlab
label_desc: Use image node_id 9 for calling the TestSpectral obj's underlying member method code with example usage: obj.test_psd() without return types