code: def test_lambertw_subnormal_k0(z):
      # Verify that subnormal inputs are handled correctly on
      # the branch k=0 (regression test for gh-16291).
      w = lambertw(z)
      # For values this small, we can be sure that numerically,
      # lambertw(z) is z.
      assert w == z
  
file_path: scipy/scipy/special/tests/test_lambertw.py
imports: import pytest
  import numpy
  from numpy.testing import assert_, assert_equal, assert_array_almost_equal
  from scipy.special import lambertw
  from numpy import nan, inf, pi, e, isnan, log, r_, array, complex128
  from scipy.special._testutils import FuncData
label_desc: Use image node_id 4 for calling a global function with example usage: test_lambertw_subnormal_k0(z) without return types