class_docstr: Test class for observation and state intercepts (which usually do not
  get tested in other models).
code: def start_params(self):
      return np.arange(6)
  
imports: import numpy
  import pandas
  import os
  import pytest
  from statsmodels.tsa.statespace import mlemodel, sarimax
  from statsmodels import datasets
  from numpy.testing import assert_equal, assert_allclose, assert_raises
label_desc: Use image node_id 3 for calling the Intercepts obj's underlying member method code with example usage: obj.start_params() and returns: np