code: def parent_commit():
      parent1 = os.environ.get("HG_PARENT1", None)
      return parent1
  
imports: from __future__ import absolute_import, print_function, division
  import difflib
  import operator
  import os
  import string
  from subprocess import Popen, PIPE
  import sys
  import tabnanny
  import tokenize
  import reindent
  from six import StringIO
label_desc: Use image node_id 5 for calling a global function with example usage: parent_commit() and returns: parent1