code: def test_bernoulli_fixed_param(posterior):
      fit = posterior.fixed_param(num_thin=2)
      assert fit["theta"].shape[-1] == 500 * 4
      assert (fit["theta"][0] == fit["theta"]).all()
  
file_path: pystan/tests/test_basic_bernoulli.py
imports: import numpy
  import pytest
  import stan
label_desc: Use image node_id 4 for calling a global function with example usage: test_bernoulli_fixed_param(posterior) without return types