contract Ownable {
    address public owner;
    address public newOwner;
    /**
      * @dev The Ownable constructor sets the original `owner` of the contract to the sender
      * account.
      */
    constructor() public {  
        owner = msg.sender;
    }

    /**
      * @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), "Address should not be 0x");
        newOwner = _newOwner;
    }
    
    function approveOwnership() public{
        require(newOwner == msg.sender);
        owner = newOwner;
    }

}
/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
function transferOwnership(address _newOwner) public onlyOwner {
    require(_newOwner != address(0), "Address should not be 0x");
    newOwner = _newOwner;
}

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