Run 2to3 on this library.
diff --git a/Lib/lib2to3/fixes/basefix.py b/Lib/lib2to3/fixes/basefix.py
index 66c448e..38666c1 100644
--- a/Lib/lib2to3/fixes/basefix.py
+++ b/Lib/lib2to3/fixes/basefix.py
@@ -108,7 +108,7 @@
         """
         name = template
         while name in self.used_names:
-            name = template + str(self.numbers.next())
+            name = template + str(next(self.numbers))
         self.used_names.add(name)
         return name