code: def _parse_index_file(filename):
      """Parse index file."""
      index = []
      for line in open(filename):
          index.append(int(line.strip()))
      return index
  
imports: import os
  import io
  import sys
  import numpy
  import pickle
  from pgl import graph
  from pgl.utils.logger import log
label_desc: Use image node_id 3 for calling a global function with example usage: _parse_index_file(filename) and returns: index