code: def test_bernoulli_to_frame(fit):
      df = fit.to_frame()
      assert 0.1 < df["theta"].mean() < 0.4
      assert 0.01 < df["theta"].var() < 0.02
  
file_path: pystan/tests/test_basic_bernoulli.py
imports: import numpy
  import pytest
  import stan
label_desc: Use image node_id 7 for calling a global function with example usage: test_bernoulli_to_frame(fit) without return types