add delete_after parameter to Webhook.send

Author: krittick

discord/webhook/async_.py

@@ -1312,6 +1312,7 @@ async def send(
         view: View = MISSING,
         thread: Snowflake = MISSING,
         wait: bool = False,
+        delete_after: float = None,
     ) -> Optional[WebhookMessage]:
         """|coro|
 
@@ -1377,7 +1378,9 @@ async def send(
             The thread to send this webhook to.
 
             .. versionadded:: 2.0
-
+        delete_after: :class:`float`
+            If provided, the number of seconds to wait in the background
+            before deleting the message we just sent.
         Raises
         --------
         HTTPException
@@ -1459,6 +1462,12 @@ async def send(
             message_id = None if msg is None else msg.id
             self._state.store_view(view, message_id)
 
+        if delete_after is not None:
+            async def delete():
+                await asyncio.sleep(delete_after)
+                await msg.delete()
+            asyncio.ensure_future(delete(), loop=self._state.loop)
+
         return msg
 
     async def fetch_message(