Discord.py TypeError: <lambda> () принимает 0 позиционных аргументов, но дан 1

Привет, я не знаю, почему этот код не работает:

class MusicPlayer():
    __slots__ = ("client", "_guild", "_ctxs", "_channel", "_cog", "np", "volume", "current", "colour", "task")
    queue = asyncio.Queue()
    next = asyncio.Event()

    def __init__(self, ctx, client):

        self.client = client
        self._guild = ctx.guild
        self._ctxs = ctx
        self._channel = ctx.channel
        self._cog = ctx.cog

        self.np = None
        self.volume = defaultvolume
        self.current = None
        self.colour = self.client.defaultcolour

        ctx.bot.loop.create_task(self.player_loop())

    async def player_loop(self):
        await self.client.wait_until_ready()

        while True:
            self.next.clear()

            try:
                async with timeout(300):
                    self.current = await queue.get()
            except asyncio.CancelledError:
                return
            except asyncio.TimeoutError:
                guild = self._guild
                vc = guild.voice_client
                self.destroy(guild)
                if not vc: return
                await self._ctxs.send(":point_right: **I disconnected myself from the **`{}`** voice channel as I was not playing audio for 5 minutes!**".format(vc.channel.name))
                return
            except:
                self.destroy(self._guild)
                await self._ctxs.send(":thumbsdown: **Error: getting next song failed!** Please retry later!")
                return

            self._ctxs.voice_client.play(self.current, after=lambda: self.client.loop.call_soon_threadsafe(next.set))
            self.current.volume = self.volume
            thumbnail = self.current.thumbnail if self.current.thumbnail else self.client.user.avatar_url
            self.colour = await self.client.get_average_colour(thumbnail)
            embednps = discord.Embed(colour=self.colour)
            embednps.add_field(name="Now Playing", value=f"```{self.current.title}```", inline=False)
            embednps.add_field(name="Link", value=f"[URL]({self.current.web_url})", inline=True)
            embednps.add_field(name="Duration", value=self.client.time_from_seconds(self.current.duration), inline=True)
            embednps.add_field(name="Channel", value=f"{self.current.uploader}", inline=False)
            embednps.set_thumbnail(url=f"{thumbnail}")
            embednps.set_footer(text=f"Requested by {self.current.requester}", icon_url=self.current.requester.avatar_url)
            self.np = await self._channel.send(embed=embednps)

            await next.wait()
            print("Terminated")

            # Cleanup player
            self.current.cleanup()
            self.current = None

    async def add_song(self, player):
        return await self.queue.put(player)

    def destroy(self, guild):
        return self.client.loop.create_task(self._cog.cleanup(guild))



@bot.command(aliases=['yt', 'youtube'])
async def play(ctx, url):
    channel = ctx.author.voice.channel
    if url is None:
        await ctx.send("Music: Please specify a Youtube URL. Syntax (!play {URL})")
        return

    if ctx.guild.voice_client is None:
        if not ctx.author.voice:
            await ctx.send("Music: Please join a Voice Channel or use join command.")
            return
        await channel.connect()
    else:
        if not ctx.author.voice:
            await ctx.send("Music: Please join a Voice Channel or use join command.")
            return
        if ctx.guild.voice_client.channel != ctx.message.author.voice.channel:
            await ctx.guild.voice_client.move_to(channel)

    async with ctx.typing():
        player = await YTDLSource.from_url(url, loop=ctx.bot.loop, stream=True)

        if ctx.guild.voice_client.is_playing():
            await MusicPlayer.add_song(MusicPlayer, player)
            await ctx.send('Music: {} has now been added to the Queue'.format(player.title))
            return

        voice_channel = ctx.guild.voice_client
        voice_channel.play(player, after=lambda: self.bot.loop.call_soon_threadsafe(MusicPlayer.next.set))
        await ctx.send('Music: Now playing {}'.format(player.title))

Кто может объяснить, почему это не работает? Консоль сообщает мне эту ошибку:

self.after(error)
TypeError: <lambda () takes 0 positional arguments but 1 was given