diff --git a/scrapy/core/downloader/handlers/__init__.py b/scrapy/core/downloader/handlers/__init__.py
index 94e0e59ef..e86680978 100644
--- a/scrapy/core/downloader/handlers/__init__.py
+++ b/scrapy/core/downloader/handlers/__init__.py
@@ -4,17 +4,17 @@ import logging
 
 from twisted.internet import defer
 
-from scrapy.exceptions import NotSupported, NotConfigured
+from scrapy import signals
+from scrapy.exceptions import NotConfigured, NotSupported
 from scrapy.utils.httpobj import urlparse_cached
 from scrapy.utils.misc import create_instance, load_object
 from scrapy.utils.python import without_none_values
-from scrapy import signals
 
 
 logger = logging.getLogger(__name__)
 
 
-class DownloadHandlers(object):
+class DownloadHandlers:
 
     def __init__(self, crawler):
         self._crawler = crawler
diff --git a/scrapy/core/downloader/handlers/datauri.py b/scrapy/core/downloader/handlers/datauri.py
index 97134e618..a45b4ff3c 100644
--- a/scrapy/core/downloader/handlers/datauri.py
+++ b/scrapy/core/downloader/handlers/datauri.py
@@ -5,7 +5,7 @@ from scrapy.responsetypes import responsetypes
 from scrapy.utils.decorators import defers
 
 
-class DataURIDownloadHandler(object):
+class DataURIDownloadHandler:
     lazy = False
 
     @defers
diff --git a/scrapy/core/downloader/handlers/ftp.py b/scrapy/core/downloader/handlers/ftp.py
index 2b22465e0..89c88ad70 100644
--- a/scrapy/core/downloader/handlers/ftp.py
+++ b/scrapy/core/downloader/handlers/ftp.py
@@ -33,8 +33,8 @@ from io import BytesIO
 from urllib.parse import unquote
 
 from twisted.internet import reactor
-from twisted.protocols.ftp import FTPClient, CommandFailed
-from twisted.internet.protocol import Protocol, ClientCreator
+from twisted.internet.protocol import ClientCreator, Protocol
+from twisted.protocols.ftp import CommandFailed, FTPClient
 
 from scrapy.http import Response
 from scrapy.responsetypes import responsetypes
diff --git a/scrapy/core/downloader/handlers/http10.py b/scrapy/core/downloader/handlers/http10.py
index 51c0acd1b..1086a6cc0 100644
--- a/scrapy/core/downloader/handlers/http10.py
+++ b/scrapy/core/downloader/handlers/http10.py
@@ -2,7 +2,7 @@
 """
 from twisted.internet import reactor
 
-from scrapy.utils.misc import load_object, create_instance
+from scrapy.utils.misc import create_instance, load_object
 from scrapy.utils.python import to_unicode
 
 
diff --git a/scrapy/core/downloader/handlers/http11.py b/scrapy/core/downloader/handlers/http11.py
index 25dc287df..d8a561792 100644
--- a/scrapy/core/downloader/handlers/http11.py
+++ b/scrapy/core/downloader/handlers/http11.py
@@ -1,27 +1,27 @@
 """Download handlers for http and https schemes"""
 
-import re
 import logging
+import re
 import warnings
 from io import BytesIO
 from time import time
 from urllib.parse import urldefrag
 
-from zope.interface import implementer
-from twisted.internet import defer, reactor, protocol
+from twisted.internet import defer, protocol, reactor
+from twisted.internet.endpoints import TCP4ClientEndpoint
+from twisted.internet.error import TimeoutError
+from twisted.web.client import Agent, HTTPConnectionPool, ResponseDone, ResponseFailed, URI
+from twisted.web.http import _DataLoss, PotentialDataLoss
 from twisted.web.http_headers import Headers as TxHeaders
 from twisted.web.iweb import IBodyProducer, UNKNOWN_LENGTH
-from twisted.internet.error import TimeoutError
-from twisted.web.http import _DataLoss, PotentialDataLoss
-from twisted.web.client import Agent, ResponseDone, HTTPConnectionPool, ResponseFailed, URI
-from twisted.internet.endpoints import TCP4ClientEndpoint
+from zope.interface import implementer
 
+from scrapy.core.downloader.tls import openssl_methods
+from scrapy.core.downloader.webclient import _parse
 from scrapy.exceptions import ScrapyDeprecationWarning
 from scrapy.http import Headers
 from scrapy.responsetypes import responsetypes
-from scrapy.core.downloader.webclient import _parse
-from scrapy.core.downloader.tls import openssl_methods
-from scrapy.utils.misc import load_object, create_instance
+from scrapy.utils.misc import create_instance, load_object
 from scrapy.utils.python import to_bytes, to_unicode