diff --git a/offlineimap/utils/const.py b/offlineimap/utils/const.py
index f4584bc..7dab07a 100644
--- a/offlineimap/utils/const.py
+++ b/offlineimap/utils/const.py
@@ -5,6 +5,7 @@
 
 import copy
 
+
 class ConstProxy(object):
     """Implements read-only access to a given object
     that can be attached to each instance only once."""
@@ -12,23 +13,19 @@ class ConstProxy(object):
     def __init__(self):
         self.__dict__['__source'] = None
 
-
     def __getattr__(self, name):
         src = self.__dict__['__source']
         if src == None:
             raise ValueError("using non-initialized ConstProxy() object")
         return copy.deepcopy(getattr(src, name))
 
-
     def __setattr__(self, name, value):
-        raise AttributeError("tried to set '%s' to '%s' for constant object"% \
-            (name, value))
-
+        raise AttributeError("tried to set '%s' to '%s' for constant object" % \
+                             (name, value))
 
     def __delattr__(self, name):
-        raise RuntimeError("tried to delete field '%s' from constant object"% \
-            (name))
-
+        raise RuntimeError("tried to delete field '%s' from constant object" % \
+                           (name))
 
     def set_source(self, source):
         """ Sets source object for this instance. """