code: def _get_root_node_info(decision_tree, feature_names=None):
      # type: (...) -> NodeInfo
      res = _get_node_info(decision_tree.tree_, 0)
      _add_feature_names(res, feature_names)
      return res
  
file_path: eli5/eli5/sklearn/treeinspect.py
imports: from __future__ import absolute_import, division
  from sklearn.base import ClassifierMixin
  from sklearn.tree import _tree, export_graphviz
  from eli5.base import TreeInfo, NodeInfo
label_desc: Use image node_id 3 for calling a global function with example usage: _get_root_node_info(decision_tree, feature_names) and returns: res