def set_journal_comment(self, comment=None):
if comment is None:<EOL><INDENT>raise NullArgument()<EOL><DEDENT>metadata = Metadata(**settings.METADATA['<STR_LIT>'])<EOL>if metadata.is_read_only():<EOL><INDENT>raise NoAccess()<EOL><DEDENT>if self._is_valid_input(comment, metadata, array=False):<EOL><INDENT>self._my_map['<STR_LIT>']['<STR_LIT:text>'] = comment<EOL><DEDENT>else:<EOL><INDENT>raise InvalidArgument()<EOL><DEDENT>
Sets a comment.

        arg:    comment (string): the new comment
        raise:  InvalidArgument - comment is invalid
        raise:  NoAccess - metadata.is_readonly() is true
        raise:  NullArgument - comment is null
        compliance: mandatory - This method must be implemented.