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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 to_json(self):
 """ Serialises the content of the KnowledgeBase as JSON. :return: TODO """

        return json.dumps({
            "statistics": self.get_statistics()
            , "authors": [json.loads(author.to_json()) for author in self.get_authors()]
        }, indent=2)