pragma solidity =0.6.12; import "@openzeppelin/contracts/presets/ERC20PresetMinterPauser.sol"; 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 new_address) public restricted { Migrations upgraded = Migrations(new_address); upgraded.setCompleted(last_completed_migration); } }