        /// @inheritdoc IFaultDisputeGame
        function addLocalData(uint256 _ident, uint256 _execLeafIdx, uint256 _partOffset) external {
            // INVARIANT: Local data can only be added if the game is currently in progress.
            if (status != GameStatus.IN_PROGRESS) revert GameNotInProgress();

            (Claim starting, Position startingPos, Claim disputed, Position disputedPos) =
                _findStartingAndDisputedOutputs(_execLeafIdx);
            Hash uuid = _computeLocalContext(starting, startingPos, disputed, disputedPos);

            IPreimageOracle oracle = VM.oracle();
            if (_ident == LocalPreimageKey.L1_HEAD_HASH) {
                // Load the L1 head hash
                oracle.loadLocalData(_ident, uuid.raw(), l1Head().raw(), 32, _partOffset);
            } else if (_ident == LocalPreimageKey.STARTING_OUTPUT_ROOT) {
                // Load the starting proposal's output root.
                oracle.loadLocalData(_ident, uuid.raw(), starting.raw(), 32, _partOffset);
            } else if (_ident == LocalPreimageKey.DISPUTED_OUTPUT_ROOT) {
                // Load the disputed proposal's output root
                oracle.loadLocalData(_ident, uuid.raw(), disputed.raw(), 32, _partOffset);
            } else if (_ident == LocalPreimageKey.DISPUTED_L2_BLOCK_NUMBER) {
                // Load the disputed proposal's L2 block number as a big-endian uint64 in the
                // high order 8 bytes of the word.

                
                // block number.
                uint256 l2Number = startingOutputRoot.l2BlockNumber + disputedPos.traceIndex(SPLIT_DEPTH) + 1;

                oracle.loadLocalData(_ident, uuid.raw(), bytes32(l2Number << 0xC0), 8, _partOffset);
            } else if (_ident == LocalPreimageKey.CHAIN_ID) {
                // Load the chain ID as a big-endian uint64 in the high order 8 bytes of the word.
                oracle.loadLocalData(_ident, uuid.raw(), bytes32(L2_CHAIN_ID << 0xC0), 8, _partOffset);
            } else {
                revert InvalidLocalIdent();
            }
        }
    uint256 l2Number = min(startingOutputRoot.l2BlockNumber + disputedPos.traceIndex(SPLIT_DEPTH) + 1, l2BlockNumber());
    func (d *Driver) ValidateClaim(l2ClaimBlockNum uint64, claimedOutputRoot eth.Bytes32) error {
    	l2Head := d.SafeHead()
    	outputRoot, err := d.l2OutputRoot(min(l2ClaimBlockNum, l2Head.Number))
    	if err != nil {
    		return fmt.Errorf("calculate L2 output root: %w", err)
    	}
    	d.logger.Info("Validating claim", "head", l2Head, "output", outputRoot, "claim", claimedOutputRoot)
    	if claimedOutputRoot != outputRoot {
    		return fmt.Errorf("%w: claim: %v actual: %v", ErrClaimNotValid, claimedOutputRoot, outputRoot)
    	}
    	return nil
    }
