new_contents: #/usr/bin/env python
  g_var = "global"
  def show_mod_var():
      try:
          print(g_var)
      except UnboundLocalError:
          print("You can not reference a global value inner function");
          pass
      # ref: https://docs.python.org/2/tutorial/classes.html#python-scopes-and-namespaces
      # Anywrite to this varalbe will cause a UnboundLocalError!!!!!
      # You can un-comment line 11 to test
      # g_var = 100
      print(g_var)
  
  print(g_var)
  show_mod_var()
  g_var = "modified"
  print(g_var)
  
  if True:
      # if block can read global
      print(g_var)
      g_var = "modified 2"
      print(g_var)
  
subject: Test module-level global scope