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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 setRemoveAction(self, action):
 """ Sets the remove action that should be taken when a model is removed from the collection generated by this reverse lookup. Valid actions are "unset" or "delete", any other values will raise an exception. :param action: <str> """

        if action not in ('unset', 'delete'):
            raise orb.errors.ValidationError('The remove action must be either "unset" or "delete"')
        else:
            self.__removeAction = action