smart-contract/contracts/Migrations.sol

pragma solidity ^0.5.0;

/* solium-disable mixedcase */
contract Migrations {
    address public owner;
    uint public last_completed_migration;

    modifier restricted() {
        if (msg.sender == owner) _;
    }

    constructor() public {
        owner = msg.sender;
    }

    function setCompleted(uint completed) public restricted {
        last_completed_migration = completed;
    }

    function upgrade(address _newAddress) public restricted {
        Migrations upgraded = Migrations(_newAddress);
        upgraded.setCompleted(last_completed_migration);
    }
}

/* solium-enable mixedcase */