5 files changed, 20 insertions, 24 deletions
diff --git a/discord/abc.py b/discord/abc.py
index 36af70bd..c9e740f2 100644
--- a/discord/abc.py
+++ b/discord/abc.py
@@ -24,14 +24,13 @@ DEALINGS IN THE SOFTWARE.
 
 from __future__ import annotations
 
-import sys
 import copy
 import asyncio
 from typing import TYPE_CHECKING, Protocol, runtime_checkable
 
 from .iterators import HistoryIterator
 from .context_managers import Typing
-from .enums import ChannelType, VideoQualityMode
+from .enums import ChannelType
 from .errors import InvalidArgument, ClientException
 from .mentions import AllowedMentions
 from .permissions import PermissionOverwrite, Permissions
@@ -692,7 +691,7 @@ class GuildChannel(Protocol):
         else:
             raise InvalidArgument('target parameter must be either Member or Role')
 
-        if isinstance(overwrite, _Undefined):
+        if overwrite is _undefined:
             if len(permissions) == 0:
                 raise InvalidArgument('No overwrite provided.')
             try:
diff --git a/discord/ext/commands/flags.py b/discord/ext/commands/flags.py
index 3aa9a65f..07c9cfc4 100644
--- a/discord/ext/commands/flags.py
+++ b/discord/ext/commands/flags.py
@@ -36,7 +36,7 @@ from discord.utils import resolve_annotation
 from .view import StringView
 from .converter import run_converters
 
-from discord.utils import maybe_coroutine
+from discord.utils import maybe_coroutine, MISSING
 from dataclasses import dataclass, field
 from typing import (
     Dict,
@@ -69,14 +69,6 @@ if TYPE_CHECKING:
     from .context import Context
 
 
-class _MissingSentinel:
-    def __repr__(self):
-        return 'MISSING'
-
-
-MISSING: Any = _MissingSentinel()
-
-
 @dataclass
 class Flag:
     """Represents a flag parameter for :class:`FlagConverter`.
diff --git a/discord/utils.py b/discord/utils.py
index d78c35a9..b2068ee5 100644
--- a/discord/utils.py
+++ b/discord/utils.py
@@ -79,6 +79,17 @@ __all__ = (
 DISCORD_EPOCH = 1420070400000
 
 
+class _MissingSentinel:
+    def __eq__(self, other):
+        return False
+
+    def __repr__(self):
+        return '...'
+
+
+MISSING: Any = _MissingSentinel()
+
+
 class _cached_property:
     def __init__(self, function):
         self.function = function
diff --git a/discord/webhook/async_.py b/discord/webhook/async_.py
index 32552455..2a42b52b 100644
--- a/discord/webhook/async_.py
+++ b/discord/webhook/async_.py
@@ -28,7 +28,6 @@ import contextvars
 import logging
 import asyncio
 import json
-import time
 import re
 
 from urllib.parse import quote as urlquote
@@ -67,16 +66,7 @@ if TYPE_CHECKING:
     from ..abc import Snowflake
     import datetime
 
-
-class _Missing:
-    def __bool__(self):
-        return False
-
-    def __repr__(self):
-        return '...'
-
-
-MISSING: Any = _Missing()
+MISSING = utils.MISSING
 
 
 class AsyncDeferredLock:
@@ -731,6 +721,7 @@ class BaseWebhook(Hashable):
             return Asset._from_default_avatar(self._state, 0)
         return Asset._from_avatar(self._state, self.id, self._avatar)
 
+
 class Webhook(BaseWebhook):
     """Represents an asynchronous Discord webhook.
 
diff --git a/discord/webhook/sync.py b/discord/webhook/sync.py
index 98bb528e..23445317 100644
--- a/discord/webhook/sync.py
+++ b/discord/webhook/sync.py
@@ -45,7 +45,7 @@ from ..message import Message
 from ..http import Route
 from ..object import Object
 
-from .async_ import BaseWebhook, handle_message_parameters, _WebhookState, MISSING
+from .async_ import BaseWebhook, handle_message_parameters, _WebhookState
 
 __all__ = (
     'SyncWebhook',
@@ -68,6 +68,8 @@ if TYPE_CHECKING:
     except ModuleNotFoundError:
         pass
 
+MISSING = utils.MISSING
+
 
 class DeferredLock:
     def __init__(self, lock: threading.Lock):
@@ -333,6 +335,7 @@ class WebhookAdapter:
         route = Route('GET', '/webhooks/{webhook_id}/{webhook_token}', webhook_id=webhook_id, webhook_token=token)
         return self.request(route, session=session)
 
+
 _context = threading.local()
 _context.adapter = WebhookAdapter()