def summarize(logger):
    """
    Creates a short summary on the actions that were logged by the given
    Logger.

    :type  logger: Logger
    :param logger: The logger that recorded what happened in the queue.
    :rtype:  string
    :return: A string summarizing the status of every performed task.
    """
    summary = []
    for log in logger.get_logs():
        thestatus = log.has_error() and log.get_error(False) or 'ok'
        name = log.get_name()
        summary.append(name + ': ' + thestatus)
    return '\n'.join(summary)