code: def test_representation_pickle():
      nobs = 10
      k_endog = 2
      arr = np.arange(nobs * k_endog).reshape(k_endog, nobs) * 1.0
      endog = np.asfortranarray(arr)
      mod = Representation(endog, k_states=2)
      pkl_mod = pickle.loads(pickle.dumps(mod))
  
      assert_equal(mod.nobs, pkl_mod.nobs)
      assert_equal(mod.k_endog, pkl_mod.k_endog)
  
      mod._initialize_representation()
      pkl_mod._initialize_representation()
      assert_equal(mod.design, pkl_mod.design)
      assert_equal(mod.obs_intercept, pkl_mod.obs_intercept)
      assert_equal(mod.initial_variance, pkl_mod.initial_variance)
  
file_path: statsmodels/statsmodels/tsa/statespace/tests/test_pickle.py
imports: import pickle
  import numpy
  import pandas
  from numpy.testing import assert_equal, assert_allclose
  import pytest
  from statsmodels.tsa.statespace import sarimax
  from statsmodels.tsa.statespace.kalman_filter import KalmanFilter
  from statsmodels.tsa.statespace.representation import Representation
  from statsmodels.tsa.statespace.structural import UnobservedComponents
  from .results import results_kalman_filter
label_desc: Use image node_id 5 for calling a global function with example usage: test_representation_pickle() without return types