def go_online(self, comment=None):
        """
        Executes a Go-Online operation on the specified node
        typically done when the node has already been forced offline
        via :func:`go_offline`

        :param str comment: (optional) comment to audit
        :raises NodeCommandFailed: online not available
        :return: None
        """
        self.make_request(
            NodeCommandFailed,
            method='update',
            resource='go_online',
            params={'comment': comment})