Run 2to3 on this library.
diff --git a/Lib/lib2to3/pgen2/driver.py b/Lib/lib2to3/pgen2/driver.py
index 77e2a40..4b5dcc0 100644
--- a/Lib/lib2to3/pgen2/driver.py
+++ b/Lib/lib2to3/pgen2/driver.py
@@ -99,7 +99,7 @@
 
     def parse_string(self, text, debug=False):
         """Parse a string and return the syntax tree."""
-        tokens = tokenize.generate_tokens(generate_lines(text).next)
+        tokens = tokenize.generate_tokens(generate_lines(text).__next__)
         return self.parse_tokens(tokens, debug)