old_contents: # encoding: utf-8
  import sys
  
  # On Python(>=2.7), sys.version_info[0] <==> sys.version_info.major
  if sys.version_info[0] == 2:
      PY3 = False
  else:
      PY3 = True
  
new_contents: # encoding: utf-8
  import sys
  
  # On Python(>=2.7), sys.version_info[0] <==> sys.version_info.major
  if sys.version_info[0] == 2:
      PY2, PY3 = True, False
      byte_type, text_type, string_type = str, unicode, basestring
  else:
      PY2, PY3 = False, True
      byte_type, text_type, string_type = bytes, str, str
  
  Bytes, Unicode, String = byte_type, text_type, string_type
  to_bytes = lambda v, e="utf-8": v.encode(e) if isinstance(v, Unicode) else v
  to_unicode = lambda v, e="utf-8": v.decode(e) if isinstance(v, Bytes) else v
  to_str = to_unicode if PY3 else to_bytes
  
subject: Add the compatible types