code: def test_powm1_exact_cases(x, y, expected):
      # Test cases where we have an exact expected value.
      p = powm1(x, y)
      assert p == expected
  
imports: import pytest
  import numpy
  from numpy.testing import assert_allclose
  from scipy.special import powm1
label_desc: Use image node_id 2 for calling a global function with example usage: test_powm1_exact_cases(x, y, expected) without return types