old_contents: import unittest
  import datetime
  from vk.users import User
  
  
  class UserTestCase(unittest.TestCase):
  
      def setUp(self):
          self.unixtime = {'time': 1506187303}
          self.unixtime_is_none = None
  
      def test_fail_if_not_convert_unixtime_to_datetime_UTC(self):
          last_seen_in_datetime = User._last_seen(self.unixtime)
          self.assertEqual(last_seen_in_datetime, datetime.datetime(2017, 9, 23, 17, 21, 43))
  
      def test_return_None_when_unixtime_is_None(self):
          last_seen_in_datetime = User._last_seen(self.unixtime_is_none)
          self.assertIsNone(last_seen_in_datetime)
  
new_contents: import unittest
  import datetime
  from vk.users import User
  
  
  class UserTestCase(unittest.TestCase):
  
      def setUp(self):
          self.unixtime = {'time': 1506187303}
          self.unixtime_is_none = None
  
      def test_fail_if_not_convert_unixtime_to_datetime_UTC(self):
          last_seen_in_datetime = User._last_seen(self.unixtime)
          self.assertEqual(last_seen_in_datetime, datetime.datetime(2017, 9, 23, 17, 21, 43))
  
      def test_return_None_when_unixtime_is_None(self):
          last_seen_in_datetime = User._last_seen(self.unixtime_is_none)
          self.assertIsNone(last_seen_in_datetime)
  
      def test_transform_sex(self):
          sex_items = {
              1: 'female',
              2: 'male'
          }
  
          sex = User._sex(1)
          self.assertEqual(sex, sex_items[1])
  
          sex = User._sex(2)
          self.assertEqual(sex, sex_items[2])
  
          sex = User._sex(3)
          self.assertIsNone(sex)
  
          sex = User._sex(None)
          self.assertIsNone(sex)
  
subject: Add test `test_transform_sex`