code: def _extract_graph_summary(graph_def):
      """Extracts useful information from the graph and returns them."""
      name_to_input_name = {}  # Keyed by the dest node name.
      name_to_node = {}  # Keyed by node name.
  
      # Keeps track of node sequences. It is important to still output the
      # operations in the original order.
      name_to_seq_num = {}  # Keyed by node name.
      seq = 0
      for node in graph_def.node:
          n = _node_name(node.name)
          name_to_node[n] = node
          name_to_input_name[n] = [_node_name(x) for x in node.input]
          # Prevent colocated nodes from being lost.
          if "_class" in node.attr:
              for colocated_node_name in node.attr["_class"].list.s:
                  name_to_input_name[n].append(
                      _get_colocated_node_name(colocated_node_name)
                  )
          name_to_seq_num[n] = seq
          seq += 1
      return name_to_input_name, name_to_node, name_to_seq_num
  
file_path: tensorflow-upstream/tensorflow/python/framework/graph_util_impl.py
imports: import copy
  import re
  from tensorflow.core.framework import graph_pb2
  from tensorflow.core.framework import node_def_pb2
  from tensorflow.python.framework import _proto_comparators
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.util import deprecation
  from tensorflow.python.util.tf_export import tf_export
label_desc: Use image node_id 5 for calling a global function with example usage: _extract_graph_summary(graph_def) and returns: name_to_input_name,  name_to_node,  name_to_seq_num