code: def test_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", data=data, ar=1, ma=1, family=Poisson()
      )
      x = model.fit("BBVI", iterations=200, quiet_progress=True)
      predictions = model.predict_is(
          h=10, fit_method="BBVI", intervals=False
      )
      assert not np.all(predictions.values == predictions.values[0])
  
imports: import numpy
  import pandas
  from pyflux.arma import ARIMAX
  from pyflux.families import Poisson
label_desc: Use image node_id 9 for calling a global function with example usage: test_predict_is_nonconstant() without return types