from trac.wiki.formatter import wiki_to_oneliner

def execute(hdf, txt, env):
    str = '<div class="system-message"><strong>Currently Not Implemented:</strong>'
    str += ' This feature is planned but is not yet implemented.'
    if txt:
        str += ' Please see ' + wiki_to_oneliner(txt,env,None) + ' for details.'
    str += '</div>'
    return str