# HG changeset patch
# User aronacher
# Date 1216073919 0
# Node ID 3eb859adc5deb1511d06c77dc9d9d1889f3f51c3
# Parent  ecf110e7f604e3038067dba9078cbab0dc693d58
Fixed a bug in plural.py that caused a traceback for some locales, changed the `__mod__` DateTimePattern to not raise exceptions but return NotImplemented.

diff --git a/babel/dates.py b/babel/dates.py
--- a/babel/dates.py
+++ b/babel/dates.py
@@ -731,7 +731,8 @@
         return self.pattern
 
     def __mod__(self, other):
-        assert type(other) is DateTimeFormat
+        if type(other) is not DateTimeFormat:
+            return NotImplemented
         return self.format % other
 
     def apply(self, datetime, locale):
diff --git a/babel/plural.py b/babel/plural.py
--- a/babel/plural.py
+++ b/babel/plural.py
@@ -351,7 +351,7 @@
     def expr(self):
         self.expect('word', 'n')
         if self.skip('word', 'mod'):
-            return 'mod', (('n', None), self.value())
+            return 'mod', (('n', ()), self.value())
         return 'n', ()
 
     def value(self):