code: def test_regression():
      estimator = lgb.LGBMRegressor(
          n_estimators=2, random_state=1, max_depth=1
      )
      utils.get_regression_model_trainer()(estimator)
  
      assembler = LightGBMModelAssembler(estimator)
      actual = assembler.assemble()
  
      expected = ast.BinNumExpr(
          ast.IfExpr(
              ast.CompExpr(
                  ast.FeatureRef(12),
                  ast.NumVal(9.725),
                  ast.CompOpType.GT,
              ),
              ast.NumVal(22.030283219508686),
              ast.NumVal(23.27840740210207),
          ),
          ast.IfExpr(
              ast.CompExpr(
                  ast.FeatureRef(5),
                  ast.NumVal(6.8375),
                  ast.CompOpType.GT,
              ),
              ast.NumVal(1.2777791671888081),
              ast.NumVal(-0.2686772850549309),
          ),
          ast.BinNumOpType.ADD,
      )
  
      assert utils.cmp_exprs(actual, expected)
  
file_path: m2cgen/tests/assemblers/test_boosting_lightgbm.py
imports: import lightgbm
  import numpy
  import pytest
  from m2cgen import ast
  from m2cgen.assemblers import LightGBMModelAssembler
  from tests import utils
label_desc: Use image node_id 3 for calling a global function with example usage: test_regression() without return types