pragma solidity >=0.5.0 <0.6.0; contract Controlled { /// @notice The address of the controller is the only address that can call /// a function with this modifier modifier onlyController { require(msg.sender == controller, "Unauthorized"); _; } address payable public controller; constructor() internal { controller = msg.sender; } /// @notice Changes the controller of the contract /// @param _newController The new controller of the contract function changeController(address payable _newController) public onlyController { controller = _newController; } }