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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 save(self, block_id, consensus_hash, ops_hash, accepted_ops, virtualchain_ops_hints, backup=False):
 """ Write out all state to the working directory. Calls the implementation's 'db_save' method to store any state for this block. Calls the implementation's 'db_continue' method at the very end, to signal to the implementation that all virtualchain state has been saved. This method can return False, in which case, indexing stops Return True on success Return False if the implementation wants to exit. Aborts on fatal error """

        assert self.setup, "Not set up yet.  Call .db_setup() first!"
        assert len(accepted_ops) == len(virtualchain_ops_hints)

        if self.read_only:
            log.error("FATAL: StateEngine is read only")
            traceback.print_stack()
            os.abort()

        if block_id < self.lastblock:
            log.error("FATAL: Already processed up to block {} (got {})".format(self.lastblock, block_id))
            traceback.print_stack()
            os.abort()
        
        # ask the implementation to save 
        if hasattr(self.impl, 'db_save'):
            rc = False
            try:
                rc = self.impl.db_save(block_id, consensus_hash, ops_hash, accepted_ops, virtualchain_ops_hints, db_state=self.state)
            except Exception as e:
                log.exception(e)
                rc = False

            if not rc:
                log.error("FATAL: Implementation failed to save state at block {}".format(block_id))
                traceback.print_stack()
                os.abort()

        # save new chainstate
        self.lastblock = block_id

        # start a transaction to store the new data
        db_con = self.db_open(self.impl, self.working_dir)
        cur = db_con.cursor()

        self.db_query_execute(cur, "BEGIN", (), verbose=False)
        
        # add chainstate
        for i, (accepted_op, virtualchain_op_hints) in enumerate(zip(accepted_ops, virtualchain_ops_hints)):

            # unpack virtualchain hints
            senders = virtualchain_op_hints['virtualchain_senders']
            data_hex = virtualchain_op_hints['virtualchain_data_hex']
            tx_hex = virtualchain_op_hints['virtualchain_txhex']
            txid = virtualchain_op_hints['virtualchain_txid']
            fee = virtualchain_op_hints['virtualchain_fee']
            opcode = virtualchain_op_hints['virtualchain_opcode']
            txindex = virtualchain_op_hints['virtualchain_txindex']
            vtxindex = i
            merkle_path = virtualchain_op_hints['virtualchain_tx_merkle_path']

            vtx_data = {
                'txid': txid,
                'senders': simplejson.dumps(senders),
                'data_hex': data_hex,
                'tx_hex': tx_hex,
                'tx_merkle_path': merkle_path,
                'fee': fee,
                'opcode': opcode,
                'txindex': txindex,
                'vtxindex': vtxindex,
                'block_id': block_id
            }
            
            self.db_chainstate_append(cur, **vtx_data)
            
        # update snapshot info
        self.db_snapshot_append(cur, block_id, consensus_hash, ops_hash, int(time.time()))
        self.db_query_execute(cur, "END", (), verbose=False)
        db_con.close()

        # make new backups and clear old ones
        self.make_backups(block_id)
        self.clear_old_backups(block_id)
        
        # ask the implementation if we should continue
        continue_indexing = True
        if hasattr(self.impl, "db_continue"):
            try:
                continue_indexing = self.impl.db_continue( block_id, consensus_hash )
            except Exception, e:
                log.exception(e)
                traceback.print_stack()
                log.error("FATAL: implementation failed db_continue")
                os.abort()

        return continue_indexing