NameError: name 'get_channel' is not defined

Bot dont send DM messages on clicking reactions. Help plz

async def on_raw_reaction_add(payload):
    emoji = payload.emoji
    channel = self.get_channel(payload.channel_id)
    message = await channel.fetch_message(payload.message_id)
    author = 774756799902908446
    if message == 830157552762224700:
        if emoji == ":flag_gb:":
            member = client.get_user(author)
            member.send("Hello")
    await message.remove_reaction(emoji, author)```