<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 async def unplonk(self, ctx, *, member: discord.Member):
 """Unbans a user from using the bot. To use this command you must have the Manage Server permission or have a Bot Admin role. """


        plonks = self.config.get('plonks', {})
        guild_id = ctx.message.server.id
        db = plonks.get(guild_id, [])

        try:
            db.remove(member.id)
        except ValueError:
            await self.bot.responses.failure(message='%s is not banned from using the bot in this server.' % member)
        else:
            plonks[guild_id] = db
            await self.config.put('plonks', plonks)
            await self.bot.responses.success(message='%s has been unbanned from using the bot in this server.' % member)