contract Ownable {
    mapping(address => bool)  internal owners;

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

    /**
     * @dev The Ownable constructor sets the original `owner` of the contract to the sender
     * account.
     */
    function Ownable() public{
        owners[msg.sender] = true;
    }

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

    function addOwner(address newAllowed) onlyOwner public {
        owners[newAllowed] = true;
    }

    function removeOwner(address toRemove) onlyOwner public {
        owners[toRemove] = false;
    }

    function isOwner() public view returns(bool){
        return owners[msg.sender] == true;
    }

}
/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
function Ownable() public{
        owners[msg.sender] = true;
    }
/**
 * @dev The Ownable constructor sets the original `owner` of the contract to the sender
 * account.
 */