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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 _prep_save(self):
 """ Prepares the bulk saver to load the trace graph info into the database. """

        log.info("Preparing bulk save.")
        self.graph.update_bulk_saver(self.bulk_saver)

        log.info(
            "Dropped %d unused preconditions, %d are missing",
            sum(len(v) for v in self.summary["precondition_entries"].values()),
            len(self.summary["missing_preconditions"]),
        )

        log.info(
            "Dropped %d unused postconditions, %d are missing",
            sum(len(v) for v in self.summary["postcondition_entries"].values()),
            len(self.summary["missing_postconditions"]),
        )
        del self.summary["postcondition_entries"]