code: def setup_class(cls):
      cls.nobs = 1000
      cls.rng = RandomState(12345)
      cls.resids = cls.rng.standard_normal(cls.nobs)
      cls.sigma2 = np.zeros_like(cls.resids)
      var = cls.resids.var()
      var_bounds = np.array([var / 1000000.0, var * 1000000.0])
      cls.var_bounds = np.ones((cls.nobs, 2)) * var_bounds
      cls.backcast = 1.0
      cls.timer_setup = """
  import numpy as np
  import arch.univariate.recursions as rec
  import arch.univariate.recursions_python as recpy
  
  nobs = 10000
  resids = np.random.standard_normal(nobs)
  sigma2 = np.zeros_like(resids)
  var = resids.var()
  backcast = 1.0
  var_bounds = np.array([var / 1000000.0, var * 1000000.0])
  var_bounds = np.ones((nobs, 2)) * var_bounds
  """
  
imports: import os
  import pickle
  import timeit
  import types
  import numpy
  from numpy.random import RandomState
  from numpy.testing import assert_allclose, assert_almost_equal
  import pytest
  from scipy.special import gamma
  import arch.univariate.recursions_python
  from arch.univariate.volatility import RiskMetrics2006
label_desc: Use image node_id 1 for calling the TestRecursions obj's underlying member method code with example usage: obj.setup_class(cls) without return types