Add default value for "whence" argument.
diff --git a/Lib/codecs.py b/Lib/codecs.py
index 092da0c..022b51b 100644
--- a/Lib/codecs.py
+++ b/Lib/codecs.py
@@ -360,7 +360,7 @@
         self.charbuffer = u""
         self.atcr = False
 
-    def seek(self, offset, whence):
+    def seek(self, offset, whence=0):
         """ Set the input stream's current position.
 
             Resets the codec buffers used for keeping state.