code: def test_fht_special_cases():
      rng = np.random.RandomState(3491349965)
  
      a = rng.standard_normal(64)
      dln = rng.uniform(-1, 1)
  
      # let xp = (mu+1+q)/2, xm = (mu+1-q)/2, M = {0, -1, -2, ...}
  
      # case 1: xp in M, xm in M => well-defined transform
      mu, bias = -4.0, 1.0
      with pytest.warns(None) as record:
          fht(a, dln, mu, bias=bias)
          assert not record, "fht warned about a well-defined transform"
  
      # case 2: xp not in M, xm in M => well-defined transform
      mu, bias = -2.5, 0.5
      with pytest.warns(None) as record:
          fht(a, dln, mu, bias=bias)
          assert not record, "fht warned about a well-defined transform"
  
      # case 3: xp in M, xm not in M => singular transform
      mu, bias = -3.5, 0.5
      with pytest.warns(Warning) as record:
          fht(a, dln, mu, bias=bias)
          assert record, "fht did not warn about a singular transform"
  
      # case 4: xp not in M, xm in M => singular inverse transform
      mu, bias = -2.5, 0.5
      with pytest.warns(Warning) as record:
          ifht(a, dln, mu, bias=bias)
          assert record, "ifht did not warn about a singular transform"
  
file_path: catboost/contrib/python/scipy/py3/scipy/fft/tests/test_fftlog.py
imports: import numpy
  from numpy.testing import assert_allclose
  import pytest
  from scipy.fft._fftlog import fht, ifht, fhtoffset
  from scipy.special import poch
label_desc: Use image node_id 3 for calling a global function with example usage: test_fht_special_cases() without return types