get rid of six

tests/fields/test_long_field.py

@@ -1,7 +1,5 @@
-# -*- coding: utf-8 -*-
-import pytest
 from bson.int64 import Int64
-import six
+import pytest
 
 from mongoengine import *
 from mongoengine.connection import get_db
@@ -24,7 +22,7 @@ class TestLongField(MongoDBTestCase):
         assert isinstance(
             db.test_long_field_considered_as_int64.find()[0]["some_long"], Int64
         )
-        assert isinstance(doc.some_long, six.integer_types)
+        assert isinstance(doc.some_long, int)
 
     def test_long_validation(self):
         """Ensure that invalid values cannot be assigned to long fields.