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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def lock_online(self, comment=None):
 """ Executes a Lock-Online operation on the specified node :param str comment: comment for audit :raises NodeCommandFailed: cannot lock online :return: None """

        self.make_request(
            NodeCommandFailed,
            method='update',
            resource='lock_online',
            params={'comment': comment})