// File: @openzeppelin/contracts/token/ERC20/ERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/ERC20.sol)

pragma solidity ^0.8.0;

import "./IERC20.sol";
import "./extensions/IERC20Metadata.sol";
import "../../utils/Context.sol";

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * The default value of {decimals} is 18. To change this, you should override
 * this function so it returns a different value.
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping(address => uint256) private _balances;

    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5.05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the default value returned by this function, unless
     * it's overridden.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual override returns (uint8) {
        return 18;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * NOTE: Does not update the allowance if the current allowance
     * is the maximum `uint256`.
     *
     * Requirements:
     *
     * - `from` and `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     * - the caller must have allowance for ``from``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address from, address to, uint256 amount) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, allowance(owner, spender) + addedValue);
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        address owner = _msgSender();
        uint256 currentAllowance = allowance(owner, spender);
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `from` to `to`.
     *
     * This internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     */
    function _transfer(address from, address to, uint256 amount) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(from, to, amount);

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
            // Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
            // decrementing then incrementing.
            _balances[to] += amount;
        }

        emit Transfer(from, to, amount);

        _afterTokenTransfer(from, to, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        unchecked {
            // Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
            _balances[account] += amount;
        }
        emit Transfer(address(0), account, amount);

        _afterTokenTransfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
            // Overflow not possible: amount <= accountBalance <= totalSupply.
            _totalSupply -= amount;
        }

        emit Transfer(account, address(0), amount);

        _afterTokenTransfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Updates `owner` s allowance for `spender` based on spent `amount`.
     *
     * Does not update the allowance amount in case of infinite allowance.
     * Revert if not enough allowance is available.
     *
     * Might emit an {Approval} event.
     */
    function _spendAllowance(address owner, address spender, uint256 amount) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - amount);
            }
        }
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual {}

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(address from, address to, uint256 amount) internal virtual {}
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 amount) external returns (bool);
}

// File: @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// File: src/Kong/Interfaces.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";

interface ITreasury {
	function mint(address to_, uint256 amount_) external;

	function TOKEN() external view returns (address);

	function excessReserves() external view returns (uint256);
}

interface IDistributor {
	function distribute() external;

	function nextRewardAt(uint256 _rate) external view returns (uint256);

	function nextReward() external view returns (uint256);
}

interface IStaking {
	function stake(address _to, uint256 _amount) external;

	function unstake(address _to, uint256 _amount, bool _rebase) external;

	function rebase() external;

	function index() external view returns (uint256);
}

interface ITOKEN is IERC20Metadata {
	function mint(address to_, uint256 amount_) external;

	function burnFrom(address account_, uint256 amount_) external;

	function burn(uint256 amount_) external;

	function uniswapV2Pair() external view returns (address);
}

interface IsStakingProtocol is IERC20 {
	function rebase(uint256 amount_, uint epoch_) external returns (uint256);

	function circulatingSupply() external view returns (uint256);

	function gonsForBalance(uint amount) external view returns (uint);

	function balanceForGons(uint gons) external view returns (uint);

	function index() external view returns (uint);
}

// File: src/Kong/StakingToken.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

/*



(Website) https://xxx.xxx
(Telegram) https://t.me/xxx
(Twitter) https://twitter.com/xxx

*/

import "./Interfaces.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

contract sToken is IsStakingProtocol, ERC20 {
	/// EVENTS ///

	event LogSupply(uint256 indexed epoch, uint256 totalSupply);
	event LogRebase(uint256 indexed epoch, uint256 rebase, uint256 index);
	event LogStakingContractUpdated(address stakingContract);

	/// MODIFIERS ///

	modifier onlyStakingContract() {
		require(msg.sender == stakingContract, "StakingContract:  call is not staking contract");
		_;
	}

	/// DATA STRUCTURES ///

	struct Rebase {
		uint256 epoch;
		uint256 rebase; // 18 decimals
		uint256 totalStakedBefore;
		uint256 totalStakedAfter;
		uint256 amountRebased;
		uint256 index;
		uint256 blockNumberOccured;
	}

	/// STATE VARIABLES ///

	address internal initializer;
	address public treasury;
	address public stakingContract; // balance used to calc rebase

	uint256 internal _totalSupply;
	uint256 internal INDEX; // Index Gons - tracks rebase growth

	uint256 private constant MAX_UINT256 = type(uint256).max;
	uint256 private constant INITIAL_FRAGMENTS_SUPPLY = 10_000_000 * 10 ** 9;

	// TOTAL_GONS is a multiple of INITIAL_FRAGMENTS_SUPPLY so that _gonsPerFragment is an integer.
	// Use the highest value that fits in a uint256 for max granularity.
	uint256 private constant TOTAL_GONS = MAX_UINT256 - (MAX_UINT256 % INITIAL_FRAGMENTS_SUPPLY);

	// MAX_SUPPLY = maximum integer < (sqrt(4*TOTAL_GONS + 1) - 1) / 2
	uint256 private constant MAX_SUPPLY = ~uint128(0); // (2^128) - 1

	uint256 private _gonsPerFragment;

	Rebase[] public rebases; // past rebase data

	mapping(address => uint256) private _gonBalances;

	mapping(address => mapping(address => uint256)) private _allowedValue;

	/// CONSTRUCTOR ///

	constructor() ERC20("Staked KONG Token", "sKONG") {
		initializer = msg.sender;
		_totalSupply = INITIAL_FRAGMENTS_SUPPLY;
		_gonsPerFragment = TOTAL_GONS / _totalSupply;
	}

	function decimals() public view virtual override returns (uint8) {
		return 9;
	}

	/// INITIALIZATION ///

	/// @notice        Sets initial index
	/// @param _index  Initial index
	function setIndex(uint256 _index) external {
		require(msg.sender == initializer, "Initializer:  caller is not initializer");
		require(INDEX == 0, "Cannot set INDEX again");
		INDEX = gonsForBalance(_index);
	}

	/// @notice                  Initialize contract
	/// @param _stakingContract  Address of staking contract
	/// @param _treasury         Address of treasury
	function initialize(address _stakingContract, address _treasury) external {
		require(msg.sender == initializer, "Initializer:  caller is not initializer");

		require(_stakingContract != address(0), "Zero address: Staking");
		stakingContract = _stakingContract;
		_gonBalances[stakingContract] = TOTAL_GONS;

		require(_treasury != address(0), "Zero address: Treasury");
		treasury = _treasury;

		emit Transfer(address(0x0), stakingContract, _totalSupply);
		emit LogStakingContractUpdated(stakingContract);

		initializer = address(0);
	}

	/// REBASE ///

	/// @notice             Increases supply
	/// @param amount_      Amount to rebase for
	/// @param epoch_       Epoch number
	/// @return _newSupply  New total supply
	function rebase(uint256 amount_, uint256 epoch_) public override onlyStakingContract returns (uint256 _newSupply) {
		uint256 rebaseAmount;
		uint256 circulatingSupply_ = circulatingSupply();
		if (amount_ == 0) {
			emit LogSupply(epoch_, _totalSupply);
			emit LogRebase(epoch_, 0, index());
			return _totalSupply;
		} else if (circulatingSupply_ > 0) {
			rebaseAmount = (amount_ * _totalSupply) / circulatingSupply_;
		} else {
			rebaseAmount = amount_;
		}

		_totalSupply = _totalSupply + rebaseAmount;

		if (_totalSupply > MAX_SUPPLY) {
			_totalSupply = MAX_SUPPLY;
		}

		_gonsPerFragment = TOTAL_GONS / _totalSupply;

		_storeRebase(circulatingSupply_, amount_, epoch_);

		return _totalSupply;
	}

	/// @notice                      Stores rebase
	/// @param previousCirculating_  Previous circ supply
	/// @param profit_               Amount of profic for epoch
	/// @param epoch_                Epoch number
	function _storeRebase(uint256 previousCirculating_, uint256 profit_, uint256 epoch_) internal {
		uint256 rebasePercent;
		if (previousCirculating_ > 0) rebasePercent = (profit_ * 1e18) / previousCirculating_;
		rebases.push(
			Rebase({
				epoch: epoch_,
				rebase: rebasePercent, // 18 decimals
				totalStakedBefore: previousCirculating_,
				totalStakedAfter: circulatingSupply(),
				amountRebased: profit_,
				index: index(),
				blockNumberOccured: block.number
			})
		);

		emit LogSupply(epoch_, _totalSupply);
		emit LogRebase(epoch_, rebasePercent, index());
	}

	/// MUTATIVE FUNCTIONS ///

	/// @notice       Transfer from msg.sender
	/// @param to     Address sending to
	/// @param value  Amount of to send
	function transfer(address to, uint256 value) public override(IERC20, ERC20) returns (bool) {
		uint256 gonValue = value * _gonsPerFragment;

		_gonBalances[msg.sender] = _gonBalances[msg.sender] - gonValue;
		_gonBalances[to] = _gonBalances[to] + gonValue;

		emit Transfer(msg.sender, to, value);
		return true;
	}

	/// @notice       Transfer
	/// @param from   Address sending from
	/// @param to     Address sending to
	/// @param value  Amount of to send
	function transferFrom(address from, address to, uint256 value) public override(IERC20, ERC20) returns (bool) {
		_allowedValue[from][msg.sender] = _allowedValue[from][msg.sender] - value;
		emit Approval(from, msg.sender, _allowedValue[from][msg.sender]);

		uint256 gonValue = gonsForBalance(value);
		_gonBalances[from] = _gonBalances[from] - gonValue;
		_gonBalances[to] = _gonBalances[to] + gonValue;

		emit Transfer(from, to, value);
		return true;
	}

	function approve(address spender, uint256 value) public override(IERC20, ERC20) returns (bool) {
		_approve(msg.sender, spender, value);
		return true;
	}

	function increaseAllowance(address spender, uint256 addedValue) public override returns (bool) {
		_approve(msg.sender, spender, _allowedValue[msg.sender][spender] + addedValue);
		return true;
	}

	function decreaseAllowance(address spender, uint256 subtractedValue) public override returns (bool) {
		uint256 oldValue = _allowedValue[msg.sender][spender];
		if (subtractedValue >= oldValue) {
			_approve(msg.sender, spender, 0);
		} else {
			_approve(msg.sender, spender, oldValue - subtractedValue);
		}
		return true;
	}

	/// INTERNAL FUNCTIONS ///

	function _approve(address owner, address spender, uint256 value) internal virtual override {
		_allowedValue[owner][spender] = value;
		emit Approval(owner, spender, value);
	}

	/// VIEW FUNCTIONS ///

	/// @notice       Returns balance of an address
	/// @param who    Address of who to get balance from
	function balanceOf(address who) public view override(IERC20, ERC20) returns (uint256) {
		return _gonBalances[who] / _gonsPerFragment;
	}

	/// @notice        Returns calculation of gons for amount of
	/// @param amount  Amount of to calculate gons for
	function gonsForBalance(uint256 amount) public view override returns (uint256) {
		return amount * _gonsPerFragment;
	}

	/// @notice      Returns calculation of balance for gons amount
	/// @param gons  Amount of gons to calculate for
	function balanceForGons(uint256 gons) public view override returns (uint256) {
		return gons / _gonsPerFragment;
	}

	/// @notice  Returns circulating supply (Total Supply - Staking Contract Balance)
	function circulatingSupply() public view override returns (uint256) {
		return _totalSupply - balanceOf(stakingContract);
	}

	/// @notice  Returns current index
	function index() public view override returns (uint256) {
		return balanceForGons(INDEX);
	}

	function allowance(address owner_, address spender) public view override(IERC20, ERC20) returns (uint256) {
		return _allowedValue[owner_][spender];
	}
}