code: def test_vector_params():
      """Sample from a program with vector params."""
      program_code = """
          parameters {
            vector[3] beta;
          }
          model {
            beta ~ normal(0, 1);
          }
      """
      posterior = stan.build(program_code)
      fit = posterior.sample()
      df = fit.to_frame()
      assert all(df.columns[-3:] == ["beta.1", "beta.2", "beta.3"])
      assert len(df["beta.1"]) > 100
  
imports: import stan
label_desc: Use image node_id 1 for calling a global function with example usage: test_vector_params() without return types