[commands] Return removed cog in Bot.remove_cog

The method now returns the removed cog, if it exists.

discord/ext/commands/bot.py

@@ -548,7 +548,7 @@ class BotBase(GroupMixin):
         return self.__cogs.get(name)
 
     def remove_cog(self, name):
-        """Removes a cog from the bot.
+        """Removes a cog from the bot and returns it.
 
         All registered commands and event listeners that the
         cog has registered will be removed as well.
@@ -559,6 +559,11 @@ class BotBase(GroupMixin):
         -----------
         name: :class:`str`
             The name of the cog to remove.
+
+        Returns
+        -------
+        Optional[:class:`.Cog`]
+             The cog that was removed. ``None`` if not found.
         """
 
         cog = self.__cogs.pop(name, None)
@@ -570,6 +575,8 @@ class BotBase(GroupMixin):
             help_command.cog = None
         cog._eject(self)
 
+        return cog
+
     @property
     def cogs(self):
         """Mapping[:class:`str`, :class:`Cog`]: A read-only mapping of cog name to cog."""