code: def test_exog_smoke(x):
      gim = ARCHInMean(SP500, constant=False, volatility=GARCH(), x=x)
      res = gim.fit(disp="off")
      x_shape = 1 if isinstance(x, pd.Series) else x.shape[1]
      assert res.params.shape[0] == 4 + x_shape
  
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 6 for calling a global function with example usage: test_exog_smoke(x) without return types