
function msgSender() internal view returns (address payable sender) {
    if (msg.sender == address(this)) {
        assembly {   sender := shr(96, calldataload(sub(calldatasize(), 20)))   }
    } else {
            sender = payable(msg.sender);
    }
    return sender;
}
// https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Context.sol
function _msgSender() internal view virtual returns (address) {
    return msg.sender;
}

function withdraw(uint256 tokenId) external override {
    require(  _msgSender() == ownerOf(tokenId), "ChildMintableERC721: INVALID_TOKEN_OWNER" ); // _msgSender()
    withdrawnTokens[tokenId] = true;
    _burn(tokenId);
}
function withdrawWithMetadata(uint256 tokenId) external override {
    require( msgSender() == ownerOf(tokenId), "ChildMintableERC721: INVALID_TOKEN_OWNER" );  // msgSender()
    withdrawnTokens[tokenId] = true;
    // Encoding metadata associated with tokenId & emitting event
    emit TransferWithMetadata( ownerOf(tokenId), address(0), tokenId, this.encodeTokenMetadata(tokenId) );
    _burn(tokenId);
}
RCNftHubL1.sol:      _setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
RCNftHubL2.sol:      _setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
RCTreasury.sol:        _setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
RCTreasury.sol:        _setupRole(UBER_OWNER,               _msgSender());
RCTreasury.sol:        _setupRole(OWNER,                         _msgSender());
RCTreasury.sol:        _setupRole(GOVERNOR,                   _msgSender());
RCTreasury.sol:        _setupRole(WHITELIST,                    _msgSender());
