diff --git a/.flake8 b/.flake8
new file mode 100644
index 0000000000..bb03d08a82
--- /dev/null
+++ b/.flake8
@@ -0,0 +1,2 @@
+[flake8]
+ignore=E123,E124,E126,E128,W503
diff --git a/__init__.py b/__init__.py
index fa3c51a2ad..6d428c03e9 100644
--- a/__init__.py
+++ b/__init__.py
@@ -33,7 +33,7 @@ def register():
         account.Journal,
         module='account_asset', type_='model')
     Pool.register(
-        purchase.PurchaseLine,
+        purchase.Line,
         module='account_asset', type_='model', depends=['purchase'])
     Pool.register(
         asset.CreateMoves,
diff --git a/asset.py b/asset.py
index a591bf7c11..e2dee1af9e 100644
--- a/asset.py
+++ b/asset.py
@@ -19,12 +19,6 @@ from trytond.wizard import (Wizard, StateView, StateTransition, StateReport,
 from trytond.tools import grouped_slice
 from trytond.modules.company import CompanyReport
 
-__all__ = ['Asset', 'AssetLine', 'AssetUpdateMove',
-    'CreateMovesStart', 'CreateMoves',
-    'UpdateAssetStart', 'UpdateAssetShowDepreciation', 'UpdateAsset',
-    'AssetDepreciationTable',
-    'PrintDepreciationTableStart', 'PrintDepreciationTable']
-
 
 def date2datetime(date):
     return datetime.datetime.combine(date, datetime.time())
@@ -67,7 +61,7 @@ class Asset(Workflow, ModelSQL, ModelView):
     supplier_invoice_line = fields.Many2One('account.invoice.line',
         'Supplier Invoice Line',
         domain=[
-            If(Eval('product', None) == None,
+            If(~Eval('product', None),
                 ('product', '=', -1),
                 ('product', '=', Eval('product', -1)),
                 ),
@@ -991,8 +985,9 @@ class AssetDepreciationTable(CompanyReport):
 
             @cached_property
             def update_lines(self):
-                filter_ = lambda l: (l.account.type.expense
-                    and self.start_date < l.move.date <= self.end_date)
+                def filter_(l):
+                    return (l.account.type.expense
+                        and self.start_date < l.move.date <= self.end_date)
                 return list(filter(filter_,
                     (l for m in self.asset.update_moves for l in m.lines)))
 
diff --git a/invoice.py b/invoice.py
index c80c430a39..9e56da4120 100644
--- a/invoice.py
+++ b/invoice.py
@@ -5,8 +5,6 @@ from trytond.pyson import Eval
 from trytond.pool import Pool, PoolMeta
 from trytond.transaction import Transaction
 
-__all__ = ['InvoiceLine']
-
 
 class InvoiceLine(metaclass=PoolMeta):
     __name__ = 'account.invoice.line'
diff --git a/product.py b/product.py
index 89a347f939..10321da4ef 100644
--- a/product.py
+++ b/product.py
@@ -7,8 +7,6 @@ from trytond.pool import PoolMeta, Pool
 from trytond.modules.account_product.product import (
     account_used, template_property)
 
-__all__ = ['Category', 'CategoryAccount', 'Template', 'Product']
-
 
 class Category(metaclass=PoolMeta):
     __name__ = 'product.category'
diff --git a/purchase.py b/purchase.py
index e8ad61255b..cb2749820d 100644
--- a/purchase.py
+++ b/purchase.py
@@ -5,14 +5,12 @@ from trytond.pool import PoolMeta
 
 from trytond.modules.account_product.exceptions import AccountError
 
-__all__ = ['PurchaseLine']
 
-
-class PurchaseLine(metaclass=PoolMeta):
+class Line(metaclass=PoolMeta):
     __name__ = 'purchase.line'
 
     def get_invoice_line(self):
-        invoice_lines = super(PurchaseLine, self).get_invoice_line()
+        invoice_lines = super().get_invoice_line()
         if (self.product
                 and self.product.type == 'assets'
                 and self.product.depreciable):
diff --git a/setup.py b/setup.py
index 14f25606c7..7a0670d04b 100755
--- a/setup.py
+++ b/setup.py
@@ -81,8 +81,8 @@ setup(name=name,
     keywords='tryton account asset',
     package_dir={'trytond.modules.account_asset': '.'},
     packages=(
-        ['trytond.modules.account_asset'] +
-        ['trytond.modules.account_asset.%s' % p for p in find_packages()]
+        ['trytond.modules.account_asset']
+        + ['trytond.modules.account_asset.%s' % p for p in find_packages()]
         ),
     package_data={
         'trytond.modules.account_asset': (info.get('xml', [])
@@ -96,7 +96,8 @@ setup(name=name,
         'Intended Audience :: Developers',
         'Intended Audience :: Financial and Insurance Industry',
         'Intended Audience :: Legal Industry',
-        'License :: OSI Approved :: GNU General Public License v3 or later (GPLv3+)',
+        'License :: OSI Approved :: '
+        'GNU General Public License v3 or later (GPLv3+)',
         'Natural Language :: Bulgarian',
         'Natural Language :: Catalan',
         'Natural Language :: Chinese (Simplified)',