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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 commit_account_vesting(self, block_height):
 """ vest any tokens at this block height """

        # save all state
        log.debug("Commit all database state before vesting")
        self.db.commit()

        if block_height in self.vesting:
            traceback.print_stack()
            log.fatal("Tried to vest tokens twice at {}".format(block_height))
            os.abort()

        # commit all vesting in one transaction
        cur = self.db.cursor()
        namedb_query_execute(cur, 'BEGIN', ())
        res = namedb_accounts_vest(cur, block_height)
        namedb_query_execute(cur, 'END', ())

        self.vesting[block_height] = True
        return True