Use zope.interface decorator

This not only makes code more pleasent to read,
but also makes the code python 3 compatible
(while maintaining python 2 compatibility).

plone/app/discussion/browser/captcha.py

@@ -18,10 +18,10 @@ from zope.interface import Interface
 from zope.publisher.interfaces.browser import IDefaultBrowserLayer
 
 
+@interface.implementer(ICaptcha)
 class Captcha(Persistent):
     """Captcha input field.
     """
-    interface.implements(ICaptcha)
     adapts(Comment)
     captcha = u""
 

plone/app/discussion/browser/traversal.py

@@ -6,13 +6,14 @@ into an actual comment object.
 from plone.app.discussion.interfaces import IConversation
 from zope.component import adapts
 from zope.component import queryAdapter
-from zope.interface import implements
+from zope.interface import implementer
 from zope.interface import Interface
 from zope.publisher.interfaces.browser import IBrowserRequest
 from zope.traversing.interfaces import ITraversable
 from zope.traversing.interfaces import TraversalError
 
 
+@implementer(ITraversable)
 class ConversationNamespace(object):
     """Allow traversal into a conversation via a ++conversation++name
     namespace. The name is the name of an adapter from context to
@@ -20,8 +21,6 @@ class ConversationNamespace(object):
     (unnamed) adapter. This is to work around a bug in OFS.Traversable which
     does not allow traversal to namespaces with an empty string name.
     """
-
-    implements(ITraversable)
     adapts(Interface, IBrowserRequest)
 
     def __init__(self, context, request=None):

plone/app/discussion/browser/validator.py

@@ -11,7 +11,7 @@ from z3c.form.interfaces import IValidator
 from zope.component import adapts
 from zope.component import getMultiAdapter
 from zope.component import queryUtility
-from zope.interface import implements
+from zope.interface import implementer
 from zope.interface import Interface
 from zope.schema.interfaces import IField
 
@@ -32,8 +32,8 @@ except ImportError:
     pass
 
 
+@implementer(IValidator)
 class CaptchaValidator(validator.SimpleFieldValidator):
-    implements(IValidator)
     adapts(Interface, IDiscussionLayer, Interface, IField, Interface)
     #       Object, Request, Form, Field, Widget,
     # We adapt the CaptchaValidator class to all form fields (IField)