def METHOD_NAME(self):
    date_string_no_Z = '2014-08-26T15:20:20.062732'
    date_string_yes_Z = '2014-08-26T15:20:20.062732Z'
    group = self.document_class.wrap({'last_modified': date_string_no_Z})
    self.assertEqual(group.to_json()['last_modified'], date_string_yes_Z)
    # iso_format can, technically, produce this if microseconds
    # happens to be exactly 0
    date_string_no_Z = '2014-08-26T15:20:20'
    date_string_yes_Z = '2014-08-26T15:20:20.000000Z'
    group = self.document_class.wrap({'last_modified': date_string_no_Z})
    self.assertEqual(group.to_json()['last_modified'], date_string_yes_Z)