Unlock the candidate config.

        Purpose: Unlocks the candidate configuration, so that other people can
               | edit the device. Requires the _session private variable to be
               | a type of a ncclient.manager.Manager.

def unlock(self):
        """ Unlock the candidate config.

        Purpose: Unlocks the candidate configuration, so that other people can
               | edit the device. Requires the _session private variable to be
               | a type of a ncclient.manager.Manager.
        """
        if isinstance(self._session, manager.Manager):
            self._session.unlock()