await outside function in python

Question

I am getting a syntaxError stating that await is outside of the function. Can anyone help me with a fix/explanation?

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!')

my_secret = os.environ('TOKEN')
client.run(os.environ('TOKEN'))