  modifier safeAllowed(uint256 _safe) {
    address _owner = _safeData[_safe].owner;
    if (msg.sender != _owner && safeCan[_owner][_safe][msg.sender] == 0) revert SafeNotAllowed();
    _;
  }
 function allowSAFE(uint256 _safe, address _usr, uint256 _ok) external safeAllowed(_safe) {
    address _owner = _safeData[_safe].owner;
    safeCan[_owner][_safe][_usr] = _ok;
    emit AllowSAFE(msg.sender, _safe, _usr, _ok);
  }
function transferSAFEOwnership(uint256 _safe, address _dst) external {
    require(msg.sender == address(vault721), 'SafeMngr: Only Vault721');

    if (_dst == address(0)) revert ZeroAddress();
    SAFEData memory _sData = _safeData[_safe];
    if (_dst == _sData.owner) revert AlreadySafeOwner();

    _usrSafes[_sData.owner].remove(_safe);
    _usrSafesPerCollat[_sData.owner][_sData.collateralType].remove(_safe);

    _usrSafes[_dst].add(_safe);
    _usrSafesPerCollat[_dst][_sData.collateralType].add(_safe);

    _safeData[_safe].owner = _dst;

    emit TransferSAFEOwnership(msg.sender, _safe, _dst);
  }
_usrSafes[B] = [123]
_usrSafesPerCollat[B][_sData.collateralType] = [123]
_safeData[123].owner = B;

safeCan[A][123][X]  // notice this is from previous allowSAFE() call
safeCan[A][123][Y]  // notice this is from previous allowSAFE() call
safeCan[A][123][X]
safeCan[A][123][Y]
