   function setMarketplace(address _marketplace) external onlyAdmin {
        marketplace = _marketplace;
    }
    function unlistVesting(address _vestingPlan, uint256 _listingId) external isFreeze { // <== contains the isFreeze modfiier
        // .... some code here .....
    }

    function spotPurchase(
        address _vestingPlan,
        uint256 _listingId,
        uint256 _amount,
        address _referral
    ) external isFreeze  { // <= contains the isFreeze modifier
        // .... some code here .....
    }
    // the onlyMarketplace modifier recognizes the new marketplace and not the old marketplace and results in a revert
    function unlistVesting(address seller, address plan, uint256 amount) external onlyMarketplace {}
    function completePurchase(address buyer, address vesting, uint256 amount) external onlyMarketplace {}

// The modifier check
    modifier onlyMarketplace() {
        require(msg.sender == marketplace, "SS_VestingManager: caller is not marketplace");
        _;
    }
