code: def get_feature_importance(self):
      return self._global_feature_importance
  
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 6 for calling the HeteroBoostingTree obj's underlying member method code with example usage: obj.get_feature_importance() and returns: self