abstract contract IStaking {
    event Staked(address indexed user, uint256 amount, uint256 total, bytes data);
    event Unstaked(address indexed user, uint256 amount, uint256 total, bytes data);

    function stake(uint256 amount, bytes calldata data) virtual external;
    function stakeFor(address user, uint256 amount, bytes calldata data) virtual external;
    function unstake(uint256 amount, bytes calldata data) virtual external;
    function totalStakedFor(address addr) virtual public view returns (uint256);
    function totalStaked() virtual public view returns (uint256);
    function token() virtual external view returns (address);

    /**
     * @return False. This application does not support staking history.
     */
    function supportsHistory() external pure returns (bool) {
        return false;
    }
}
/**
 * @title Staking interface, as defined by EIP-900.
 * @dev https://github.com/ethereum/EIPs/blob/master/EIPS/eip-900.md
 */
function supportsHistory() external pure returns (bool) {
    return false;
}

/**
 * @return False. This application does not support staking history.
 */