Migrate to python 3.

configuration.py

@@ -13,8 +13,7 @@ SALE_MARGIN_METHOD = [
 sale_margin_method = fields.Selection(SALE_MARGIN_METHOD, 'Sale Margin Method')
 
 
-class Configuration:
+class Configuration(metaclass=PoolMeta):
-    __metaclass__ = PoolMeta
     __name__ = 'sale.configuration'
     sale_margin_method = fields.MultiValue(sale_margin_method)
 
@@ -31,8 +30,7 @@ class Configuration:
             'sale_margin_method').default_sale_margin_method()
 
 
-class ConfigurationSaleMethod:
+class ConfigurationSaleMethod(metaclass=PoolMeta):
-    __metaclass__ = PoolMeta
     __name__ = 'sale.configuration.sale_method'
     sale_margin_method = sale_margin_method
 

sale.py

@@ -11,8 +11,7 @@ from trytond.modules.product import price_digits
 __all__ = ['Sale', 'SaleLine']
 
 
-class Sale:
+class Sale(metaclass=PoolMeta):
-    __metaclass__ = PoolMeta
     __name__ = 'sale.sale'
     margin = fields.Function(fields.Numeric('Margin',
             digits=(16, Eval('currency_digits', 2),),
@@ -80,8 +79,7 @@ class Sale:
                     })
 
 
-class SaleLine:
+class SaleLine(metaclass=PoolMeta):
-    __metaclass__ = PoolMeta
     __name__ = 'sale.line'
     cost_price = fields.Numeric('Cost Price', digits=price_digits,
         states={

setup.py

@@ -7,10 +7,7 @@ from setuptools import setup
 import re
 import os
 import io
-try:
+from configparser import ConfigParser
-    from configparser import ConfigParser
-except ImportError:
-    from ConfigParser import ConfigParser
 
 MODULE = 'sale_margin'
 PREFIX = 'trytonzz'