code: def test_2_predict_is_nonconstant():
      """
      We should not really have predictions that are constant (should be some difference)...
      This captures bugs with the predict function not iterating forward
      """
      model = ARIMAX(formula="y ~ x1 + x2", data=data, ar=2, ma=2)
      x = model.fit()
      predictions = model.predict_is(h=10, intervals=False)
      assert not np.all(predictions.values == predictions.values[0])
  
imports: import numpy
  import pandas
  from pyflux.arma import ARIMAX
label_desc: Use image node_id 25 for calling a global function with example usage: test_2_predict_is_nonconstant() without return types