discord.ext.commands.errors.CommandNotFound: Command “play” is not found

i was making a music bot with DISCORD PY and everytime i try to run the play command it says discord.ext.commands.errors.CommandNotFound: Command “play” is not found. i am following a tutorial from youtube, since im basically clueless about python. link to the YT tutorial

here is my code

import discord
from discord.ext import commands
import youtube_dl

class music(commands.Cog):
  def init(self,client):
    self.client = client

  @commands.command()
  async def join(self,ctx):
    if ctx.author.voice is None:
        await ctx.send("you need to join a voice channel dumbass") 
    voice_channel = ctx.author.voice.channel
    if ctx.voice_client is None:
        await voice_channel.connect()
    else:
      await ctx.voice_client.move_to(voice_channel)

  @commands.command()
  async def disconnect(self,ctx):
    await ctx.voice_client.disconnect()

  @commands.command
  async def play(self,ctx,url):
    ctx.voice_client.stop()
    FFMPEG_OPTIONS = {'before_options': '-reconnect 1 -reconnect_streamed 1 -reconnect_delay_max 5', 'options': 'vn'}
    YDL_OPTIONS = {'format':"bestaudio"}
    vc = ctx.voice_client

    with youtube_dl.YoutubeDL(YDL_OPTIONS) as ydl:
      info = ydl.extract_info(url, download=False)
      url2 = info['formats'][0]['url']
      source = await discord.FFmpegOpusAudio.from_probe(url2,**FFMPEG_OPTIONS)
      vc.play(source) 


  @commands.command()
  async def pause(self,ctx):
    await ctx.voice_client.pause() 
    await ctx.send("paused")

  @commands.command()
  async def resume(self,ctx):
    await ctx.voice_client.resume() 
    await ctx.send("resuming..")


def setup(client):
  client.add_cog(music(client))

any help would be appreciated!