code: def test_warnings_nonstationary_garch(setup):
      garch = GARCH()
      parameters = np.array([0.1, 0.2, 0.8, 4.0, 0.5])
      skewstud = SkewStudent()
      with pytest.warns(InitialValueWarning):
          garch.simulate(
              parameters, 1000, skewstud.simulate([4.0, 0.5])
          )
  
imports: import types
  from typing import NamedTuple
  import warnings
  import numpy
  from numpy.random import RandomState
  from numpy.testing import assert_allclose, assert_almost_equal, assert_array_equal, assert_equal
  import pytest
  from scipy.special import gamma, gammaln
  from arch.univariate import ZeroMean
  from arch.univariate.distribution import Normal, SkewStudent, StudentsT
  import arch.univariate.recursions_python
  from arch.univariate.volatility import APARCH, ARCH, EGARCH, FIGARCH, GARCH, HARCH, ConstantVariance, EWMAVariance, FixedVariance, MIDASHyperbolic, RiskMetrics2006
  from arch.utility.exceptions import InitialValueWarning
label_desc: Use image node_id 15 for calling a global function with example usage: test_warnings_nonstationary_garch(setup) without return types