Index: ndiff/ndiff.py
--- ndiff/ndiff.py.orig
+++ ndiff/ndiff.py
@@ -32,6 +32,8 @@ verbose = False
 
 NDIFF_XML_VERSION = "1"
 
+def cmp(x, y):
+    return (x > y) - (x < y)
 
 class OverrideEntityResolver(xml.sax.handler.EntityResolver):
     """This class overrides the default behavior of xml.sax to download
@@ -160,11 +162,11 @@ class Host(object):
         return state is None or state in self.extraports
 
     def extraports_string(self):
-        list = [(count, state) for (state, count) in list(self.extraports.items())]
+        mylist = [(count, state) for (state, count) in list(self.extraports.items())]
         # Reverse-sort by count.
-        list.sort(reverse=True)
+        mylist.sort(reverse=True)
         return ", ".join(
-                ["%d %s ports" % (count, state) for (count, state) in list])
+                ["%d %s ports" % (count, state) for (count, state) in mylist])
 
     def state_to_dom_fragment(self, document):
         frag = document.createDocumentFragment()
@@ -183,7 +185,7 @@ class Host(object):
 
     def extraports_to_dom_fragment(self, document):
         frag = document.createDocumentFragment()
-        for state, count in list(self.extraports.items()):
+        for state, count in mylist(self.extraports.items()):
             elem = document.createElement("extraports")
             elem.setAttribute("state", state)
             elem.setAttribute("count", str(count))