Flake8 cleanup

dataset/persistence/table.py

@@ -1,5 +1,4 @@
 import logging
-from itertools import count
 from hashlib import sha1
 
 from sqlalchemy.sql import and_, expression

dataset/persistence/util.py

@@ -1,5 +1,4 @@
 from datetime import datetime
-from inspect import isgenerator
 
 try:
     from collections import OrderedDict