Fix lint.

src/allmydata/test/test_helper.py

@@ -1,14 +1,7 @@
 """
 Ported to Python 3.
 """
-from __future__ import absolute_import
+from __future__ import annotations
-from __future__ import division
-from __future__ import print_function
-from __future__ import unicode_literals
-
-from future.utils import PY2
-if PY2:
-    from future.builtins import filter, map, zip, ascii, chr, hex, input, next, oct, open, pow, round, super, bytes, dict, list, object, range, str, max, min  # noqa: F401
 
 import os
 from struct import (
@@ -17,13 +10,8 @@ from struct import (
 from functools import (
     partial,
 )
-import attr
 
-try:
+import attr
-    from typing import List
-    from allmydata.introducer.client import IntroducerClient
-except ImportError:
-    pass
 
 from twisted.internet import defer
 from twisted.trial import unittest
@@ -35,6 +23,7 @@ from eliot.twisted import (
     inline_callbacks,
 )
 
+from allmydata.introducer.client import IntroducerClient
 from allmydata.crypto import aes
 from allmydata.storage.server import (
     si_b2a,
@@ -132,7 +121,7 @@ class FakeCHKCheckerAndUEBFetcher(object):
         ))
 
 class FakeClient(service.MultiService):
-    introducer_clients = []  # type: List[IntroducerClient]
+    introducer_clients : list[IntroducerClient] = []
     DEFAULT_ENCODING_PARAMETERS = {"k":25,
                                    "happy": 75,
                                    "n": 100,