def command_not_found(self, string):
return '<STR_LIT>'.format(string)<EOL>
|maybecoro|

        A method called when a command is not found in the help command.
        This is useful to override for i18n.

        Defaults to ``No command called {0} found.``

        Parameters
        ------------
        string: :class:`str`
            The string that contains the invalid command. Note that this has
            had mentions removed to prevent abuse.

        Returns
        ---------
        :class:`str`
            The string to use when a command has not been found.