contract Ownable {

    // Owner of the contract
    address private _owner;

    /**
    * @dev Event to show ownership has been transferred
    * @param previousOwner representing the address of the previous owner
    * @param newOwner representing the address of the new owner
    */
    event OwnershipTransferred(address previousOwner, address newOwner);

    /**
    * @dev The constructor sets the original owner of the contract to the sender account.
    */
    constructor() public {
        setOwner(msg.sender);
    }

    /**
   * @dev Tells the address of the owner
   * @return the address of the owner
   */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Sets a new owner address
     */
    function setOwner(address newOwner) internal {
        _owner = newOwner;
    }

    /**
    * @dev Throws if called by any account other than the owner.
    */
    modifier onlyOwner() {
        require(msg.sender == owner());
        _;
    }

    /**
     * @dev Allows the current owner to transfer control of the contract to a newOwner.
     * @param newOwner The address to transfer ownership to.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        require(newOwner != address(0));
        emit OwnershipTransferred(owner(), newOwner);
        setOwner(newOwner);
    }
}
/**
 * @title Ownable
 * @dev The Ownable contract from https://github.com/zeppelinos/labs/blob/master/upgradeability_ownership/contracts/ownership/Ownable.sol
 * branch: master commit: 3887ab77b8adafba4a26ace002f3a684c1a3388b modified to:
 * 1) Add emit prefix to OwnershipTransferred event (7/13/18)
 * 2) Replace constructor with constructor syntax (7/13/18)
 * 3) consolidate OwnableStorage into this contract
 *
 * From https://github.com/centrehq/centre-tokens
 * branch: master commit: 3ba876b5e96eec6955733e7e008d85f419ec44a5
 */
function transferOwnership(address newOwner) public onlyOwner {
    require(newOwner != address(0));
    emit OwnershipTransferred(owner(), newOwner);
    setOwner(newOwner);
}

/**
 * @dev Allows the current owner to transfer control of the contract to a newOwner.
 * @param newOwner The address to transfer ownership to.
 */