diff --git a/cybertools/external/base.py b/cybertools/external/base.py
index 9a9c97a..dde3671 100644
--- a/cybertools/external/base.py
+++ b/cybertools/external/base.py
@@ -1,40 +1,21 @@
-#
-#  Copyright (c) 2009 Helmut Merz helmutm@cy55.de
-#
-#  This program is free software; you can redistribute it and/or modify
-#  it under the terms of the GNU General Public License as published by
-#  the Free Software Foundation; either version 2 of the License, or
-#  (at your option) any later version.
-#
-#  This program is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-#  GNU General Public License for more details.
-#
-#  You should have received a copy of the GNU General Public License
-#  along with this program; if not, write to the Free Software
-#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
-#
-"""
-Base implementation for import adapters.
+# cybertools.external.base
 
-$Id$
+""" Base implementation for import adapters.
 """
 
-from cStringIO import StringIO
+from io import StringIO
 from logging import getLogger
 
 from zope import component
-from zope.interface import implements
+from zope.interface import implementer
 from zope.cachedescriptors.property import Lazy
 
 from cybertools.external.interfaces import IReader, ILoader
 
 
+@implementer(IReader)
 class BaseReader(object):
 
-    implements(IReader)
-
     def __init__(self, context):
         self.context = context
 
@@ -42,10 +23,9 @@ class BaseReader(object):
         return []
 
 
+@implementer(ILoader)
 class BaseLoader(object):
 
-    implements(ILoader)
-
     def __init__(self, context):
         self.context = context
         self.changes = []
diff --git a/cybertools/external/element.py b/cybertools/external/element.py
index 7e17a0e..3448a1b 100644
--- a/cybertools/external/element.py
+++ b/cybertools/external/element.py
@@ -1,33 +1,14 @@
-#
-#  Copyright (c) 2010 Helmut Merz helmutm@cy55.de
-#
-#  This program is free software; you can redistribute it and/or modify
-#  it under the terms of the GNU General Public License as published by
-#  the Free Software Foundation; either version 2 of the License, or
-#  (at your option) any later version.
-#
-#  This program is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-#  GNU General Public License for more details.
-#
-#  You should have received a copy of the GNU General Public License
-#  along with this program; if not, write to the Free Software
-#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
-#
+# cybertools.external.element
 
-"""
-Basic implementation of the elements used for the intermediate format for export
+""" Basic implementation of the elements used for the intermediate format for export
 and import of objects.
-
-$Id$
 """
 
 import os
 from zope import component
 from zope.cachedescriptors.property import Lazy
 from zope.dottedname.resolve import resolve
-from zope.interface import Interface, implements
+from zope.interface import Interface, implementer
 from zope.traversing.api import getName, traverse
 
 from cybertools.composer.interfaces import IInstance
@@ -35,10 +16,9 @@ from cybertools.composer.schema.interfaces import ISchemaFactory
 from cybertools.external.interfaces import IElement
 
 
+@implementer(IElement)
 class Element(dict):
 
-    implements(IElement)
-
     encoding = 'UTF-8'
     type = ''
     identifierName = ''