contract Ownable {

    address public owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor (address initialOwner) {
        owner = initialOwner;
        emit OwnershipTransferred(address(0), owner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        emit OwnershipTransferred(owner, newOwner);
        owner = newOwner;
    }

    modifier onlyOwner() {
        require(owner == msg.sender, "not owner");
        _;
    }
}
/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
function transferOwnership(address newOwner) public onlyOwner {
    emit OwnershipTransferred(owner, newOwner);
    owner = newOwner;
}

/**
 * @dev Transfers ownership of the contract to a new account (`newOwner`).
 * Can only be called by the current owner.
 */