code: def test_var_c():
      test = "c"
  
      # VAR(2), constant trend, no exog
      results = results_var_R.res_c
      mod = varmax.VARMAX(
          endog, order=(2, 0), trend="c", loglikelihood_burn=2
      )
      res = mod.smooth(results["params"])
  
      assert_allclose(res.llf, results["llf"])
  
      # Forecast
      columns = [
          "{}.fcast.{}.fcst".format(test, name)
          for name in endog.columns
      ]
      assert_allclose(
          res.forecast(10), results_var_R_output[columns].iloc[:10]
      )
  
      # IRF
      check_irf(test, mod, results)
  
file_path: statsmodels/statsmodels/tsa/statespace/tests/test_var.py
imports: import os
  import numpy
  from numpy.testing import assert_allclose
  import pandas
  from statsmodels.tsa.statespace import varmax
  from .results import results_var_R
label_desc: Use image node_id 3 for calling a global function with example usage: test_var_c() without return types