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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 internal_link_sets(self):
 """ Gets the InternalLinkSets API client. Returns: InternalLinkSets: """

        if not self.__internal_link_sets:
            self.__internal_link_sets = InternalLinkSets(self.__connection)
        return self.__internal_link_sets