code: def _gen_random_signal():
      lengths = testing.shaped_random((8, 200, 20))
      for x in lengths:
          yield x
  
imports: from math import pi
  import pytest
  import cupy
  import numpy
  from cupy import testing
  from cupy.testing import assert_allclose
  import cupyx.scipy.fft
  import cupyx.scipy.signal
label_desc: Use image node_id 5 for calling a global function with example usage: _gen_random_signal() without return types