Need help with this, sry new to scripting and stuff

import discord
import os

client = discord.Client()

@client.event
async def on_ready():
 print('We have logged in as {0.user}'.format(client))

@client.event
async def on_message(message):
 if message.author == client.user: 
   return

 if message.content.startswith('$hello'):
   await message.channel.send('Hello!')

client.run(os.getenv('TOKEN'))

plz tell me what part is wrong here, wjen i tried to run the program it says there is an error in 18th line.

Hello there,

I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.

You can also use the “preformatted text” tool in the editor (</>) to add backticks around text.

See this post to find the backtick on your keyboard.
Note: Backticks (`) are not single quotes (’).