method .index removed from Python3 string module; not needed anyway

tldp/doctypes/common.py

@@ -2,7 +2,6 @@
 
 from __future__ import absolute_import, division, print_function
 
-import string
 from ..utils import logger
 
 
@@ -11,10 +10,10 @@ class SignatureChecker(object):
     @classmethod
     def signatureLocation(cls, f):
         f.seek(0)
-        buf = f.read(1024)
+        buf = f.read(1024).lower()
         for sig in cls.signatures:
             try:
-                sindex = string.index(buf.lower(), sig.lower())
+                sindex = buf.index(sig.lower())
                 logger.debug("Found signature %s in %s at %s; doctype %s.",
                              sig, f.name, sindex, cls)
                 return sindex