SupplyChain.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
...

  // 6th step in supply chain process
    function processedItemByDistributor(uint256 _productCode, uint256 slices)
        public
        onlyDistributor // check _msgSender() belongs to DistributorRole
        receivedByDistributor(_productCode)
        verifyCaller(items[_productCode].ownerID) // check _msgSender() is owner
    {
        items[_productCode].itemState = State.ProcessedByDistributor; // update state
        items[_productCode].productSliced = slices; // add slice amount
        emit ProcessedByDistributor(_productCode);
    }

    // 7th step in supply chain process
    function packageItemByDistributor(uint256 _productCode)
        public
        onlyDistributor // check _msgSender() belongs to DistributorRole
        processByDistributor(_productCode)
        verifyCaller(items[_productCode].ownerID) // check _msgSender() is owner
    {
        items[_productCode].itemState = State.PackageByDistributor;
        emit PackagedByDistributor(_productCode);
    }

    // 8th step in supply chain process
    function sellItemByDistributor(uint256 _productCode, uint256 _price)
        public
        onlyDistributor // check _msgSender() belongs to DistributorRole
        packagedByDistributor(_productCode)
        verifyCaller(items[_productCode].ownerID) // check _msgSender() is owner
    {
        items[_productCode].itemState = State.ForSaleByDistributor;
        items[_productCode].productPrice = _price;
        emit ForSaleByDistributor(productCode);
    }
  ...