|coro|

        The actual implementation of the help command.

        It is not recommended to override this method and instead change
        the behaviour through the methods that actually get dispatched.

        - :meth:`send_bot_help`
        - :meth:`send_cog_help`
        - :meth:`send_group_help`
        - :meth:`send_command_help`
        - :meth:`get_destination`
        - :meth:`command_not_found`
        - :meth:`subcommand_not_found`
        - :meth:`send_error_message`
        - :meth:`on_help_command_error`
        - :meth:`prepare_help_command`

async def command_callback(self, ctx, *, command=None):
        """|coro|

        The actual implementation of the help command.

        It is not recommended to override this method and instead change
        the behaviour through the methods that actually get dispatched.

        - :meth:`send_bot_help`
        - :meth:`send_cog_help`
        - :meth:`send_group_help`
        - :meth:`send_command_help`
        - :meth:`get_destination`
        - :meth:`command_not_found`
        - :meth:`subcommand_not_found`
        - :meth:`send_error_message`
        - :meth:`on_help_command_error`
        - :meth:`prepare_help_command`
        """
        await self.prepare_help_command(ctx, command)
        bot = ctx.bot

        if command is None:
            mapping = self.get_bot_mapping()
            return await self.send_bot_help(mapping)

        # Check if it's a cog
        cog = bot.get_cog(command)
        if cog is not None:
            return await self.send_cog_help(cog)

        maybe_coro = discord.utils.maybe_coroutine

        # If it's not a cog then it's a command.
        # Since we want to have detailed errors when someone
        # passes an invalid subcommand, we need to walk through
        # the command group chain ourselves.
        keys = command.split(' ')
        cmd = bot.all_commands.get(keys[0])
        if cmd is None:
            string = await maybe_coro(self.command_not_found, self.remove_mentions(keys[0]))
            return await self.send_error_message(string)

        for key in keys[1:]:
            try:
                found = cmd.all_commands.get(key)
            except AttributeError:
                string = await maybe_coro(self.subcommand_not_found, cmd, self.remove_mentions(key))
                return await self.send_error_message(string)
            else:
                if found is None:
                    string = await maybe_coro(self.subcommand_not_found, cmd, self.remove_mentions(key))
                    return await self.send_error_message(string)
                cmd = found

        if isinstance(cmd, Group):
            return await self.send_group_help(cmd)
        else:
            return await self.send_command_help(cmd)