contract Ownable {
    address private _owner;
    address private _pendingOwner;

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

    /**
     * @dev The Ownable constructor sets the original `owner` of the contract to the sender
     * account.
     */
    function initializeOwnable() internal {
        require(_owner == address(0), "already initialized");
        _owner = msg.sender;
        emit OwnershipTransferred(address(0), msg.sender);
    }


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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "msg.sender is not owner");
        _;
    }

    /**
     * @return true if `msg.sender` is the owner of the contract.
     */
    function isOwner() public view returns (bool) {
        return 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 {
        _pendingOwner = newOwner;
    }

    function receiveOwnership() public {
        require(msg.sender == _pendingOwner, "only pending owner can call this function");
        _transferOwnership(_pendingOwner);
        _pendingOwner = address(0);
    }

    /**
     * @dev Transfers control of the contract to a newOwner.
     * @param newOwner The address to transfer ownership to.
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0));
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }

    uint256[50] private __gap;
}
/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 * 
 * @dev Completely default OpenZeppelin.
 */
function isOwner() public view returns (bool) {
        return msg.sender == _owner;

    }
/**
 * @return true if `msg.sender` is the owner of the contract.
 */