code: def test_powm1(x, y, expected, rtol):
      p = powm1(x, y)
      assert_allclose(p, expected, rtol=rtol)
  
imports: import pytest
  import numpy
  from numpy.testing import assert_allclose
  from scipy.special import powm1
label_desc: Use image node_id 1 for calling a global function with example usage: test_powm1(x, y, expected, rtol) without return types