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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 index(self) -> dict: """ Return dict mapping content sequence numbers to schema keys. :return: dict mapping sequence numbers to schema keys """


        LOGGER.debug('SchemaCache.index >>>')

        rv = self._seq_no2schema_key
        LOGGER.debug('SchemaCache.index <<< %s', rv)
        return rv