    function executeMetaTransaction(
        MetaAction memory metaAction,
        bytes32 r,
        bytes32 s,
        uint8 v
    ) external payable returns (bytes memory) {
        require(
            _verify(metaAction.from, metaAction, r, s, v),
            "signer and signature don't match"
        );

        uint256 currentNonce = _nonces[metaAction.from];

        // intentionally allow this to overflow to save gas,
        // and it's impossible for someone to do 2 ^ 256 - 1 meta txs
        unchecked {
            _nonces[metaAction.from] = currentNonce + 1;
        }

        // Append the metaAction.from at the end so that it can be extracted later
        // from the calling context (see _msgSender() below)
        (bool success, bytes memory returnData) = address(this).call(
            abi.encodePacked(
                abi.encodeWithSelector(
                    IController(address(this)).operate.selector,
                    metaAction.actions
                ),
                metaAction.from
            )
        );

        require(success, "unsuccessful function call");
        emit MetaTransactionExecuted(
            metaAction.from,
            payable(msg.sender),
            currentNonce
        );
        return returnData;
    }
