function approveHash(bytes32 _hash, bool _bool) external override { //++++++++++++++++++++
    address _sender = _msgSender();
    // Allowing anyone to sign, as its hard to add restrictions here.
    // Store _hash as signed for sender.
    approvedHashes[_sender][_hash] = _bool; //+++++++++++++++++++

    emit ApproveHash(_hash, _sender, _bool); //++++++++++++++++++++++
}
