code: def print_forest(self):
      idx = 0
      for tree in self._trees:
          print("tree {}: ".format(idx))
          idx += 1
          tree.print_tree()
          print()
  
file_path: FATE/python/fate/ml/ensemble/algo/secureboost/hetero/_base.py
imports: from typing import List
  import functools
  from fate.arch.dataframe import DataFrame
  from fate.ml.abc.module import HeteroModule, Model
  from fate.ml.ensemble.learner.decision_tree.tree_core.decision_tree import FeatureImportance, Node
  from typing import Dict
  import numpy
label_desc: Use image node_id 7 for calling the HeteroBoostingTree obj's underlying member method code with example usage: obj.print_forest() without return types