code: def test_fit_matrix_draw_contents(fit):
      assert fit is not None
      offset = len(fit.sample_and_sampler_param_names)
      assert fit._draws.shape == (
          offset + K * D,
          num_samples,
          num_chains,
      )
      chain = fit._draws[:, :, 0]
      # stored in column-major order
      assert -1 < chain[offset + 0, :].mean() < 1
      assert -1 < chain[offset + 1, :].mean() < 1
      assert -1 < chain[offset + 2, :].mean() < 1
      assert 4 < chain[offset + 3, :].mean() < 6
      assert 4 < chain[offset + 4, :].mean() < 6
      assert 4 < chain[offset + 5, :].mean() < 6
      assert -1 < chain[offset + 6, :].mean() < 1
      assert -1 < chain[offset + 7, :].mean() < 1
      assert -1 < chain[offset + 8, :].mean() < 1
      assert -1 < chain[offset + 9, :].mean() < 1
      assert -1 < chain[offset + 10, :].mean() < 1
      assert -1 < chain[offset + 11, :].mean() < 1
      beta = fit["beta"]
      assert beta.shape == (K, D, num_samples * num_chains)
  
imports: import pytest
  import stan
label_desc: Use image node_id 4 for calling a global function with example usage: test_fit_matrix_draw_contents(fit) without return types