diff --git a/__init__.py b/__init__.py
index 546a623cd0..0f3c012179 100644
--- a/__init__.py
+++ b/__init__.py
@@ -1,5 +1,5 @@
-#This file is part of Tryton.  The COPYRIGHT file at the top level of
-#this repository contains the full copyright notices and license terms.
+# This file is part of Tryton.  The COPYRIGHT file at the top level of
+# this repository contains the full copyright notices and license terms.
 
 from trytond.pool import Pool
 from .dunning import *
diff --git a/account.py b/account.py
index 67bfb725bf..847a9c06f2 100644
--- a/account.py
+++ b/account.py
@@ -1,8 +1,7 @@
-#This file is part of Tryton.  The COPYRIGHT file at the top level of
-#this repository contains the full copyright notices and license terms.
+# This file is part of Tryton.  The COPYRIGHT file at the top level of
+# this repository contains the full copyright notices and license terms.
 from trytond.pool import Pool, PoolMeta
 from trytond.model import fields
-from trytond.transaction import Transaction
 
 
 __all__ = ['Configuration', 'MoveLine']
diff --git a/dunning.py b/dunning.py
index 58f8fdc57b..46084698d7 100644
--- a/dunning.py
+++ b/dunning.py
@@ -1,5 +1,5 @@
-#This file is part of Tryton.  The COPYRIGHT file at the top level of
-#this repository contains the full copyright notices and license terms.
+# This file is part of Tryton.  The COPYRIGHT file at the top level of
+# this repository contains the full copyright notices and license terms.
 from collections import defaultdict
 
 from sql import Null
diff --git a/party.py b/party.py
index 49ef6f01d9..eb3fefc1b4 100644
--- a/party.py
+++ b/party.py
@@ -1,5 +1,5 @@
-#This file is part of Tryton.  The COPYRIGHT file at the top level of
-#this repository contains the full copyright notices and license terms.
+# This file is part of Tryton.  The COPYRIGHT file at the top level of
+# this repository contains the full copyright notices and license terms.
 from trytond.model import fields
 from trytond.pool import PoolMeta
 
diff --git a/setup.py b/setup.py
index 4735c52633..4f91fbd1f0 100644
--- a/setup.py
+++ b/setup.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
-#This file is part of Tryton.  The COPYRIGHT file at the top level of
-#this repository contains the full copyright notices and license terms.
+# This file is part of Tryton.  The COPYRIGHT file at the top level of
+# this repository contains the full copyright notices and license terms.
 
 from setuptools import setup
 import re
diff --git a/tests/__init__.py b/tests/__init__.py
index cafbb27aeb..cab2de6a89 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -1,5 +1,5 @@
-#This file is part of Tryton.  The COPYRIGHT file at the top level of
-#this repository contains the full copyright notices and license terms.
+# This file is part of Tryton.  The COPYRIGHT file at the top level of
+# this repository contains the full copyright notices and license terms.
 
 from .test_account_dunning import suite
 
diff --git a/tests/test_account_dunning.py b/tests/test_account_dunning.py
index 2d0ffb4f92..fcfe733d48 100644
--- a/tests/test_account_dunning.py
+++ b/tests/test_account_dunning.py
@@ -1,5 +1,5 @@
-#This file is part of Tryton.  The COPYRIGHT file at the top level of
-#this repository contains the full copyright notices and license terms.
+# This file is part of Tryton.  The COPYRIGHT file at the top level of
+# this repository contains the full copyright notices and license terms.
 import unittest
 import doctest
 import trytond.tests.test_tryton