string compatibility of python3 and python2

gistfile1.txt

   PY2 = sys.version_info[0] == 2
   if PY2:                                                                                                                                                                                                
       text_type = unicode     
       string_types = (unicode, str)
       from cStringIO import StringIO as NativeBytesIO
   else:                       
       text_type = str         
       string_types = (str,)   
       from io import BytesIO as NativeBytesIO