function verifyMultiSig(
      address toAddress,
      bytes32 operationHash,
      bytes signature,
      uint expireTime,
      uint sequenceId
  ) private returns (address) {

    var otherSigner = recoverAddressFromSignature(operationHash, signature);

    
    if (safeMode && !isSigner(toAddress)) {
      
      revert();
    }
    
    if (expireTime < block.timestamp) {
      
      revert();
    }

    
    tryInsertSequenceId(sequenceId);

    if (!isSigner(otherSigner)) {
      
      revert();
    }
    if (otherSigner == msg.sender) {
      
      revert();
    }

    return otherSigner;
  }