code: def test_not_updateable():
      class NonUpdateableGARCH(GARCH):
          _updatable = False
  
          def __init__(self):
              super().__init__()
              self._volatility_updater = None
  
      nug = NonUpdateableGARCH()
      with pytest.raises(NotImplementedError):
          nug.volatility_updater
      with pytest.raises(ValueError, match="The volatility process"):
          ARCHInMean(SP500, volatility=nug)
  
file_path: arch/arch/tests/univariate/test_arch_in_mean.py
imports: import numpy
  import pandas
  import pytest
  from arch.data import sp500
  from arch.univariate import ARCHInMean, Normal
  from arch.univariate.volatility import ARCH, EGARCH, FIGARCH, GARCH, HARCH, EWMAVariance, MIDASHyperbolic, RiskMetrics2006
label_desc: Use image node_id 12 for calling a global function with example usage: test_not_updateable() without return types