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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 get_dependencies(self):
 """ Returns the character ids this tag refers to """

        s = super(SWFTimelineContainer, self).get_dependencies()
        for dt in self.all_tags_of_type(DefinitionTag):
            s.update(dt.get_dependencies())
        return s