code: def _is8bitstring(s):
      if isinstance(s, str):
          try:
              unicode(s, "us-ascii")
          except UnicodeError:
              return True
      return False
  
imports: import re
  import sys
  import time
  import random
  import warnings
  from cStringIO import StringIO
  from email.header import Header
label_desc: Use image node_id 1 for calling a global function with example usage: _is8bitstring(s) and returns: False, True