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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 add_veto(self, reason):
 """Adds a veto on this event. in reason of type str Reason for veto, could be null or empty string. """

        if not isinstance(reason, basestring):
            raise TypeError("reason can only be an instance of type basestring")
        self._call("addVeto",
                     in_p=[reason])