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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_initial_belief(self):
 """ add initial belief tag to pomdpx model Return string containing the xml for initial belief tag """

        initial_belief = self.model['initial_state_belief']
        for condition in initial_belief:
            condprob = etree.SubElement(self.initial_belief, 'CondProb')
            self.add_conditions(condition, condprob)
        return self.__str__(self.initial_belief)[:-1]