removed unused imports

asset.py

@@ -6,11 +6,11 @@
 from trytond.model import ModelView, ModelSQL, fields, SymbolMixin
 from trytond.transaction import Transaction
 from trytond.pool import Pool
-from trytond.pyson import Eval, Bool, And, If, Date
+from trytond.pyson import Eval, Bool, If, Date
 from trytond.report import Report
 
 from decimal import Decimal
-from datetime import time, datetime
+from datetime import time
 from sql.functions import CurrentDate, CurrentTimestamp, Round, Extract
 from sql.conditionals import Case, Coalesce, NullIf
 from sql import Literal

diagram.py

@@ -3,13 +3,11 @@
 # The COPYRIGHT file at the top level of this repository contains the
 # full copyright notices and license terms.
 
-from trytond.model import ModelView, ModelSQL, fields
-from trytond.transaction import Transaction
+from trytond.model import fields
 from trytond.pool import Pool, PoolMeta
 from trytond.pyson import Eval
 from sql.functions import Function
 from datetime import timedelta
-from decimal import Decimal
 
 
 class Concat2(Function):

identifier.py

@@ -3,7 +3,6 @@
 # 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
 
 

onlinesource.py

@@ -7,8 +7,7 @@ from string import Template
 import requests, logging, html2text, re
 from datetime import datetime
 from decimal import Decimal
-from trytond.model import ModelView, ModelSQL, fields, Unique, Check
-from trytond.transaction import Transaction
+from trytond.model import ModelView, ModelSQL, fields
 from trytond.pool import Pool
 from trytond.pyson import Eval, Bool
 from trytond.i18n import gettext