--- a/entities/adapters.py	Tue Dec 15 08:55:58 2015 +0100
+++ b/entities/adapters.py	Wed Dec 09 16:32:57 2015 +0100
@@ -1,4 +1,4 @@
-# copyright 2010-2013 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2010-2015 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
 #
 # This file is part of CubicWeb.
@@ -18,19 +18,15 @@
 """some basic entity adapter implementations, for interfaces used in the
 framework itself.
 """
-
-__docformat__ = "restructuredtext en"
 from cubicweb import _
 
 from itertools import chain
-from warnings import warn
 from hashlib import md5
 
 from logilab.mtconverter import TransformError
 from logilab.common.decorators import cached
 
-from cubicweb import ValidationError, view, ViolatedConstraint
-from cubicweb.schema import CONSTRAINTS
+from cubicweb import ValidationError, view, ViolatedConstraint, UniqueTogetherError
 from cubicweb.predicates import is_instance, relation_possible, match_exception
 
 
@@ -63,8 +59,8 @@
         NOTE: the dictionary keys should match the list returned by the
         `allowed_massmail_keys` method.
         """
-        return dict( (attr, getattr(self.entity, attr))
-                     for attr in self.allowed_massmail_keys() )
+        return dict((attr, getattr(self.entity, attr))
+                    for attr in self.allowed_massmail_keys())
 
 
 class INotifiableAdapter(view.EntityAdapter):
@@ -156,24 +152,27 @@
             if role == 'subject':
                 for entity_ in getattr(entity, rschema.type):
                     merge_weight_dict(words, entity_.cw_adapt_to('IFTIndexable').get_words())
-            else: # if role == 'object':
+            else:  # if role == 'object':
                 for entity_ in getattr(entity, 'reverse_%s' % rschema.type):
                     merge_weight_dict(words, entity_.cw_adapt_to('IFTIndexable').get_words())
         return words
 
+
 def merge_weight_dict(maindict, newdict):
     for weight, words in newdict.items():
         maindict.setdefault(weight, []).extend(words)
 
+
 class IDownloadableAdapter(view.EntityAdapter):
     """interface for downloadable entities"""
     __regid__ = 'IDownloadable'
     __abstract__ = True
 
-    def download_url(self, **kwargs): # XXX not really part of this interface
+    def download_url(self, **kwargs):  # XXX not really part of this interface
         """return a URL to download entity's content
 
-        It should be a unicode object containing url-encoded ASCII."""
+        It should be a unicode object containing url-encoded ASCII.
+        """
         raise NotImplementedError
 
     def download_content_type(self):
@@ -192,6 +191,7 @@
         """return actual data (bytes) of the downloadable content"""
         raise NotImplementedError
 
+
 # XXX should propose to use two different relations for children/parent
 class ITreeAdapter(view.EntityAdapter):
     """This adapter provides a tree interface.
@@ -339,7 +339,7 @@
             try:
                 # check we are not jumping to another tree
                 if (adapter.tree_relation != self.tree_relation or
-                    adapter.child_role != self.child_role):
+                        adapter.child_role != self.child_role):
                     break
                 entity = adapter.parent()
                 adapter = entity.cw_adapt_to('ITree')
@@ -377,7 +377,6 @@
 
 # error handling adapters ######################################################
 
-from cubicweb import UniqueTogetherError
 
 class IUserFriendlyError(view.EntityAdapter):
     __regid__ = 'IUserFriendlyError'
@@ -408,13 +407,14 @@
     __select__ = match_exception(ViolatedConstraint)
 
     def raise_user_exception(self):
-        _ = self._cw._
         cstrname = self.exc.cstrname
         eschema = self.entity.e_schema
         for rschema, attrschema in eschema.attribute_definitions():
             rdef = rschema.rdef(eschema, attrschema)
             for constraint in rdef.constraints:
-                if cstrname == 'cstr' + md5((eschema.type + rschema.type + constraint.type() + (constraint.serialize() or '')).encode('ascii')).hexdigest():
+                if cstrname == 'cstr' + md5(
+                        (eschema.type + rschema.type + constraint.type() +
+                         (constraint.serialize() or '')).encode('ascii')).hexdigest():
                     break
             else:
                 continue