async def jsk_cancel(self, ctx: commands.Context, *, index: int):
        """
        Cancels a task with the given index.

        If the index passed is -1, will cancel the last task instead.
        """

        if not self.tasks:
            return await ctx.send("No tasks to cancel.")

        if index == -1:
            task = self.tasks.pop()
        else:
            task = discord.utils.get(self.tasks, index=index)
            if task:
                self.tasks.remove(task)
            else:
                return await ctx.send("Unknown task.")

        task.task.cancel()
        return await ctx.send(f"Cancelled task {task.index}: `{task.ctx.command.qualified_name}`,"
                              f" invoked at {task.ctx.message.created_at.strftime('%Y-%m-%d %H:%M:%S')} UTC")
Cancels a task with the given index.

        If the index passed is -1, will cancel the last task instead.