pragma solidity ^0.4.18;
/*
MIT License

Copyright (c) 2018 TrustToken

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

contract DelegateERC20 {
  function delegateTotalSupply() public view returns (uint256);
  function delegateBalanceOf(address who) public view returns (uint256);
  function delegateTransfer(address to, uint256 value, address origSender) public returns (bool);
  function delegateAllowance(address owner, address spender) public view returns (uint256);
  function delegateTransferFrom(address from, address to, uint256 value, address origSender) public returns (bool);
  function delegateApprove(address spender, uint256 value, address origSender) public returns (bool);
  function delegateIncreaseApproval(address spender, uint addedValue, address origSender) public returns (bool);
  function delegateDecreaseApproval(address spender, uint subtractedValue, address origSender) public returns (bool);
}

library SafeMath {

  /**
  * @dev Multiplies two numbers, throws on overflow.
  */
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }
    uint256 c = a * b;
    assert(c / a == b);
    return c;
  }

  /**
  * @dev Integer division of two numbers, truncating the quotient.
  */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return c;
  }

  /**
  * @dev Substracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  /**
  * @dev Adds two numbers, throws on overflow.
  */
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }
}

contract Ownable {
  address public owner;


  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 {
    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));
    OwnershipTransferred(owner, newOwner);
    owner = newOwner;
  }

}

contract Pausable is Ownable {
  event Pause();
  event Unpause();

  bool public paused = false;


  /**
   * @dev Modifier to make a function callable only when the contract is not paused.
   */
  modifier whenNotPaused() {
    require(!paused);
    _;
  }

  /**
   * @dev Modifier to make a function callable only when the contract is paused.
   */
  modifier whenPaused() {
    require(paused);
    _;
  }

  /**
   * @dev called by the owner to pause, triggers stopped state
   */
  function pause() onlyOwner whenNotPaused public {
    paused = true;
    Pause();
  }

  /**
   * @dev called by the owner to unpause, returns to normal state
   */
  function unpause() onlyOwner whenPaused public {
    paused = false;
    Unpause();
  }
}

contract CanReclaimToken is Ownable {
  using SafeERC20 for ERC20Basic;

  /**
   * @dev Reclaim all ERC20Basic compatible tokens
   * @param token ERC20Basic The address of the token contract
   */
  function reclaimToken(ERC20Basic token) external onlyOwner {
    uint256 balance = token.balanceOf(this);
    token.safeTransfer(owner, balance);
  }

}

contract Claimable is Ownable {
  address public pendingOwner;

  /**
   * @dev Modifier throws if called by any account other than the pendingOwner.
   */
  modifier onlyPendingOwner() {
    require(msg.sender == pendingOwner);
    _;
  }

  /**
   * @dev Allows the current owner to set the pendingOwner address.
   * @param newOwner The address to transfer ownership to.
   */
  function transferOwnership(address newOwner) onlyOwner public {
    pendingOwner = newOwner;
  }

  /**
   * @dev Allows the pendingOwner address to finalize the transfer.
   */
  function claimOwnership() onlyPendingOwner public {
    OwnershipTransferred(owner, pendingOwner);
    owner = pendingOwner;
    pendingOwner = address(0);
  }
}

contract AddressList is Claimable {
    string public name;
    mapping (address => bool) public onList;

    function AddressList(string _name, bool nullValue) public {
        name = _name;
        onList[0x0] = nullValue;
    }
    event ChangeWhiteList(address indexed to, bool onList);

    // Set whether _to is on the list or not. Whether 0x0 is on the list
    // or not cannot be set here - it is set once and for all by the constructor.
    function changeList(address _to, bool _onList) onlyOwner public {
        require(_to != 0x0);
        if (onList[_to] != _onList) {
            onList[_to] = _onList;
            ChangeWhiteList(_to, _onList);
        }
    }
}

contract HasNoContracts is Ownable {

  /**
   * @dev Reclaim ownership of Ownable contracts
   * @param contractAddr The address of the Ownable to be reclaimed.
   */
  function reclaimContract(address contractAddr) external onlyOwner {
    Ownable contractInst = Ownable(contractAddr);
    contractInst.transferOwnership(owner);
  }
}

contract HasNoEther is Ownable {

  /**
  * @dev Constructor that rejects incoming Ether
  * @dev The `payable` flag is added so we can access `msg.value` without compiler warning. If we
  * leave out payable, then Solidity will allow inheriting contracts to implement a payable
  * constructor. By doing it this way we prevent a payable constructor from working. Alternatively
  * we could use assembly to access msg.value.
  */
  function HasNoEther() public payable {
    require(msg.value == 0);
  }

  /**
   * @dev Disallows direct send by settings a default function without the `payable` flag.
   */
  function() external {
  }

  /**
   * @dev Transfer all Ether held by the contract to the owner.
   */
  function reclaimEther() external onlyOwner {
    assert(owner.send(this.balance));
  }
}

contract HasNoTokens is CanReclaimToken {

 /**
  * @dev Reject all ERC223 compatible tokens
  * @param from_ address The address that is transferring the tokens
  * @param value_ uint256 the amount of the specified token
  * @param data_ Bytes The data passed from the caller.
  */
  function tokenFallback(address from_, uint256 value_, bytes data_) external {
    from_;
    value_;
    data_;
    revert();
  }

}

contract NoOwner is HasNoEther, HasNoTokens, HasNoContracts {
}

contract AllowanceSheet is Claimable {
    using SafeMath for uint256;

    mapping (address => mapping (address => uint256)) public allowanceOf;

    function addAllowance(address tokenHolder, address spender, uint256 value) public onlyOwner {
        allowanceOf[tokenHolder][spender] = allowanceOf[tokenHolder][spender].add(value);
    }

    function subAllowance(address tokenHolder, address spender, uint256 value) public onlyOwner {
        allowanceOf[tokenHolder][spender] = allowanceOf[tokenHolder][spender].sub(value);
    }

    function setAllowance(address tokenHolder, address spender, uint256 value) public onlyOwner {
        allowanceOf[tokenHolder][spender] = value;
    }
}

contract BalanceSheet is Claimable {
    using SafeMath for uint256;

    mapping (address => uint256) public balanceOf;

    function addBalance(address addr, uint256 value) public onlyOwner {
        balanceOf[addr] = balanceOf[addr].add(value);
    }

    function subBalance(address addr, uint256 value) public onlyOwner {
        balanceOf[addr] = balanceOf[addr].sub(value);
    }

    function setBalance(address addr, uint256 value) public onlyOwner {
        balanceOf[addr] = value;
    }
}

contract ERC20Basic {
  function totalSupply() public view returns (uint256);
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
}

contract BasicToken is ERC20Basic, Claimable {
  using SafeMath for uint256;

  BalanceSheet public balances;

  uint256 totalSupply_;

  function setBalanceSheet(address sheet) external onlyOwner {
    balances = BalanceSheet(sheet);
    balances.claimOwnership();
  }

  /**
  * @dev total number of tokens in existence
  */
  function totalSupply() public view returns (uint256) {
    return totalSupply_;
  }

  /**
  * @dev transfer token for a specified address
  * @param _to The address to transfer to.
  * @param _value The amount to be transferred.
  */
  function transfer(address _to, uint256 _value) public returns (bool) {
    transferAllArgsNoAllowance(msg.sender, _to, _value);
    return true;
  }

  function transferAllArgsNoAllowance(address _from, address _to, uint256 _value) internal {
    require(_to != address(0));
    require(_from != address(0));
    require(_value <= balances.balanceOf(_from));

    // SafeMath.sub will throw if there is not enough balance.
    balances.subBalance(_from, _value);
    balances.addBalance(_to, _value);
    Transfer(_from, _to, _value);
  }

  /**
  * @dev Gets the balance of the specified address.
  * @param _owner The address to query the the balance of.
  * @return An uint256 representing the amount owned by the passed address.
  */
  function balanceOf(address _owner) public view returns (uint256 balance) {
    return balances.balanceOf(_owner);
  }
}

contract BurnableToken is BasicToken {

  event Burn(address indexed burner, uint256 value);

  /**
   * @dev Burns a specific amount of tokens.
   * @param _value The amount of token to be burned.
   */
  function burn(uint256 _value) public {
    require(_value <= balances.balanceOf(msg.sender));
    // no need to require value <= totalSupply, since that would imply the
    // sender's balance is greater than the totalSupply, which *should* be an assertion failure

    address burner = msg.sender;
    balances.subBalance(burner, _value);
    totalSupply_ = totalSupply_.sub(_value);
    Burn(burner, _value);
    Transfer(burner, address(0), _value);
  }
}

contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender) public view returns (uint256);
  function transferFrom(address from, address to, uint256 value) public returns (bool);
  function approve(address spender, uint256 value) public returns (bool);
  event Approval(address indexed owner, address indexed spender, uint256 value);
}

library SafeERC20 {
  function safeTransfer(ERC20Basic token, address to, uint256 value) internal {
    assert(token.transfer(to, value));
  }

  function safeTransferFrom(ERC20 token, address from, address to, uint256 value) internal {
    assert(token.transferFrom(from, to, value));
  }

  function safeApprove(ERC20 token, address spender, uint256 value) internal {
    assert(token.approve(spender, value));
  }
}

contract StandardToken is ERC20, BasicToken {

  AllowanceSheet public allowances;

  function setAllowanceSheet(address sheet) external onlyOwner {
    allowances = AllowanceSheet(sheet);
    allowances.claimOwnership();
  }

  /**
   * @dev Transfer tokens from one address to another
   * @param _from address The address which you want to send tokens from
   * @param _to address The address which you want to transfer to
   * @param _value uint256 the amount of tokens to be transferred
   */
  function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
    transferAllArgsYesAllowance(_from, _to, _value, msg.sender);
    return true;
  }

  function transferAllArgsYesAllowance(address _from, address _to, uint256 _value, address spender) internal {
    require(_value <= allowances.allowanceOf(_from, spender));

    allowances.subAllowance(_from, spender, _value);
    transferAllArgsNoAllowance(_from, _to, _value);
  }

  /**
   * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
   *
   * 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
   * @param _spender The address which will spend the funds.
   * @param _value The amount of tokens to be spent.
   */
  function approve(address _spender, uint256 _value) public returns (bool) {
    approveAllArgs(_spender, _value, msg.sender);
    return true;
  }

  function approveAllArgs(address _spender, uint256 _value, address _tokenHolder) internal {
    allowances.setAllowance(_tokenHolder, _spender, _value);
    Approval(_tokenHolder, _spender, _value);
  }

  /**
   * @dev Function to check the amount of tokens that an owner allowed to a spender.
   * @param _owner address The address which owns the funds.
   * @param _spender address The address which will spend the funds.
   * @return A uint256 specifying the amount of tokens still available for the spender.
   */
  function allowance(address _owner, address _spender) public view returns (uint256) {
    return allowances.allowanceOf(_owner, _spender);
  }

  /**
   * @dev Increase the amount of tokens that an owner allowed to a spender.
   *
   * approve should be called when allowed[_spender] == 0. To increment
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param _spender The address which will spend the funds.
   * @param _addedValue The amount of tokens to increase the allowance by.
   */
  function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
    increaseApprovalAllArgs(_spender, _addedValue, msg.sender);
    return true;
  }

  function increaseApprovalAllArgs(address _spender, uint _addedValue, address tokenHolder) internal {
    allowances.addAllowance(tokenHolder, _spender, _addedValue);
    Approval(tokenHolder, _spender, allowances.allowanceOf(tokenHolder, _spender));
  }

  /**
   * @dev Decrease the amount of tokens that an owner allowed to a spender.
   *
   * approve should be called when allowed[_spender] == 0. To decrement
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param _spender The address which will spend the funds.
   * @param _subtractedValue The amount of tokens to decrease the allowance by.
   */
  function decreaseApproval(address _spender, uint _subtractedValue) public returns (bool) {
    decreaseApprovalAllArgs(_spender, _subtractedValue, msg.sender);
    return true;
  }

  function decreaseApprovalAllArgs(address _spender, uint _subtractedValue, address tokenHolder) internal {
    uint oldValue = allowances.allowanceOf(tokenHolder, _spender);
    if (_subtractedValue > oldValue) {
      allowances.setAllowance(tokenHolder, _spender, 0);
    } else {
      allowances.subAllowance(tokenHolder, _spender, _subtractedValue);
    }
    Approval(tokenHolder, _spender, allowances.allowanceOf(tokenHolder, _spender));
  }

}

contract CanDelegate is StandardToken {
    // If this contract needs to be upgraded, the new contract will be stored
    // in 'delegate' and any ERC20 calls to this contract will be delegated to that one.
    DelegateERC20 public delegate;

    event DelegatedTo(address indexed newContract);

    // Can undelegate by passing in newContract = address(0)
    function delegateToNewContract(DelegateERC20 newContract) public onlyOwner {
        delegate = newContract;
        DelegatedTo(delegate);
    }

    // If a delegate has been designated, all ERC20 calls are forwarded to it
    function transfer(address to, uint256 value) public returns (bool) {
        if (delegate == address(0)) {
            return super.transfer(to, value);
        } else {
            return delegate.delegateTransfer(to, value, msg.sender);
        }
    }

    function transferFrom(address from, address to, uint256 value) public returns (bool) {
        if (delegate == address(0)) {
            return super.transferFrom(from, to, value);
        } else {
            return delegate.delegateTransferFrom(from, to, value, msg.sender);
        }
    }

    function balanceOf(address who) public view returns (uint256) {
        if (delegate == address(0)) {
            return super.balanceOf(who);
        } else {
            return delegate.delegateBalanceOf(who);
        }
    }

    function approve(address spender, uint256 value) public returns (bool) {
        if (delegate == address(0)) {
            return super.approve(spender, value);
        } else {
            return delegate.delegateApprove(spender, value, msg.sender);
        }
    }

    function allowance(address _owner, address spender) public view returns (uint256) {
        if (delegate == address(0)) {
            return super.allowance(_owner, spender);
        } else {
            return delegate.delegateAllowance(_owner, spender);
        }
    }

    function totalSupply() public view returns (uint256) {
        if (delegate == address(0)) {
            return super.totalSupply();
        } else {
            return delegate.delegateTotalSupply();
        }
    }

    function increaseApproval(address spender, uint addedValue) public returns (bool) {
        if (delegate == address(0)) {
            return super.increaseApproval(spender, addedValue);
        } else {
            return delegate.delegateIncreaseApproval(spender, addedValue, msg.sender);
        }
    }

    function decreaseApproval(address spender, uint subtractedValue) public returns (bool) {
        if (delegate == address(0)) {
            return super.decreaseApproval(spender, subtractedValue);
        } else {
            return delegate.delegateDecreaseApproval(spender, subtractedValue, msg.sender);
        }
    }
}

contract StandardDelegate is StandardToken, DelegateERC20 {
    address public delegatedFrom;

    modifier onlySender(address source) {
        require(msg.sender == source);
        _;
    }

    function setDelegatedFrom(address addr) onlyOwner public {
        delegatedFrom = addr;
    }

    // All delegate ERC20 functions are forwarded to corresponding normal functions
    function delegateTotalSupply() public view returns (uint256) {
        return totalSupply();
    }

    function delegateBalanceOf(address who) public view returns (uint256) {
        return balanceOf(who);
    }

    function delegateTransfer(address to, uint256 value, address origSender) onlySender(delegatedFrom) public returns (bool) {
        transferAllArgsNoAllowance(origSender, to, value);
        return true;
    }

    function delegateAllowance(address owner, address spender) public view returns (uint256) {
        return allowance(owner, spender);
    }

    function delegateTransferFrom(address from, address to, uint256 value, address origSender) onlySender(delegatedFrom) public returns (bool) {
        transferAllArgsYesAllowance(from, to, value, origSender);
        return true;
    }

    function delegateApprove(address spender, uint256 value, address origSender) onlySender(delegatedFrom) public returns (bool) {
        approveAllArgs(spender, value, origSender);
        return true;
    }

    function delegateIncreaseApproval(address spender, uint addedValue, address origSender) onlySender(delegatedFrom) public returns (bool) {
        increaseApprovalAllArgs(spender, addedValue, origSender);
        return true;
    }

    function delegateDecreaseApproval(address spender, uint subtractedValue, address origSender) onlySender(delegatedFrom) public returns (bool) {
        decreaseApprovalAllArgs(spender, subtractedValue, origSender);
        return true;
    }
}

contract PausableToken is StandardToken, Pausable {

  function transfer(address _to, uint256 _value) public whenNotPaused returns (bool) {
    return super.transfer(_to, _value);
  }

  function transferFrom(address _from, address _to, uint256 _value) public whenNotPaused returns (bool) {
    return super.transferFrom(_from, _to, _value);
  }

  function approve(address _spender, uint256 _value) public whenNotPaused returns (bool) {
    return super.approve(_spender, _value);
  }

  function increaseApproval(address _spender, uint _addedValue) public whenNotPaused returns (bool success) {
    return super.increaseApproval(_spender, _addedValue);
  }

  function decreaseApproval(address _spender, uint _subtractedValue) public whenNotPaused returns (bool success) {
    return super.decreaseApproval(_spender, _subtractedValue);
  }
}

contract USDDigital is StandardDelegate, PausableToken, BurnableToken, NoOwner, CanDelegate {
    string public name = "USDDigital";
    string public symbol = "USDD";
    uint8 public constant decimals = 18;

    AddressList public canReceiveMintWhiteList;
    AddressList public canBurnWhiteList;
    AddressList public blackList;
    AddressList public noFeesList;
    uint256 public burnMin = 10000 * 10**uint256(decimals);
    uint256 public burnMax = 20000000 * 10**uint256(decimals);

    uint80 public transferFeeNumerator = 7;
    uint80 public transferFeeDenominator = 10000;
    uint80 public mintFeeNumerator = 0;
    uint80 public mintFeeDenominator = 10000;
    uint256 public mintFeeFlat = 0;
    uint80 public burnFeeNumerator = 0;
    uint80 public burnFeeDenominator = 10000;
    uint256 public burnFeeFlat = 0;
    address public staker;

    event ChangeBurnBoundsEvent(uint256 newMin, uint256 newMax);
    event Mint(address indexed to, uint256 amount);
    event WipedAccount(address indexed account, uint256 balance);

    function USDDigital() public {
        totalSupply_ = 0;
        staker = msg.sender;
    }

    function setLists(AddressList _canReceiveMintWhiteList, AddressList _canBurnWhiteList, AddressList _blackList, AddressList _noFeesList) onlyOwner public {
        canReceiveMintWhiteList = _canReceiveMintWhiteList;
        canBurnWhiteList = _canBurnWhiteList;
        blackList = _blackList;
        noFeesList = _noFeesList;
    }

    function changeName(string _name, string _symbol) onlyOwner public {
        name = _name;
        symbol = _symbol;
    }

    //Burning functions as withdrawing money from the system. The platform will keep track of who burns coins,
    //and will send them back the equivalent amount of money (rounded down to the nearest cent).
    function burn(uint256 _value) public {
        require(canBurnWhiteList.onList(msg.sender));
        require(_value >= burnMin);
        require(_value <= burnMax);
        uint256 fee = payStakingFee(msg.sender, _value, burnFeeNumerator, burnFeeDenominator, burnFeeFlat, 0x0);
        uint256 remaining = _value.sub(fee);
        super.burn(remaining);
    }

    //Create _amount new tokens and transfer them to _to.
    //Based on code by OpenZeppelin: https://github.com/OpenZeppelin/zeppelin-solidity/blob/master/contracts/token/MintableToken.sol
    function mint(address _to, uint256 _amount) onlyOwner public {
        require(canReceiveMintWhiteList.onList(_to));
        totalSupply_ = totalSupply_.add(_amount);
        balances.addBalance(_to, _amount);
        Mint(_to, _amount);
        Transfer(address(0), _to, _amount);
        payStakingFee(_to, _amount, mintFeeNumerator, mintFeeDenominator, mintFeeFlat, 0x0);
    }

    //Change the minimum and maximum amount that can be burned at once. Burning
    //may be disabled by setting both to 0 (this will not be done under normal
    //operation, but we can't add checks to disallow it without losing a lot of
    //flexibility since burning could also be as good as disabled
    //by setting the minimum extremely high, and we don't want to lock
    //in any particular cap for the minimum)
    function changeBurnBounds(uint newMin, uint newMax) onlyOwner public {
        require(newMin <= newMax);
        burnMin = newMin;
        burnMax = newMax;
        ChangeBurnBoundsEvent(newMin, newMax);
    }

    // transfer and transferFrom are both dispatched to this function, so we
    // check blacklist and pay staking fee here.
    function transferAllArgsNoAllowance(address _from, address _to, uint256 _value) internal {
        require(!blackList.onList(_from));
        require(!blackList.onList(_to));
        super.transferAllArgsNoAllowance(_from, _to, _value);
        payStakingFee(_to, _value, transferFeeNumerator, transferFeeDenominator, 0, _from);
    }

    function wipeBlacklistedAccount(address account) public onlyOwner {
        require(blackList.onList(account));
        uint256 oldValue = balanceOf(account);
        balances.setBalance(account, 0);
        totalSupply_ = totalSupply_.sub(oldValue);
        WipedAccount(account, oldValue);
    }

    function payStakingFee(address payer, uint256 value, uint80 numerator, uint80 denominator, uint256 flatRate, address otherParticipant) private returns (uint256) {
        if (noFeesList.onList(payer) || noFeesList.onList(otherParticipant)) {
            return 0;
        }
        uint256 stakingFee = value.mul(numerator).div(denominator).add(flatRate);
        if (stakingFee > 0) {
            super.transferAllArgsNoAllowance(payer, staker, stakingFee);
        }
        return stakingFee;
    }

    function changeStakingFees(uint80 _transferFeeNumerator,
                                 uint80 _transferFeeDenominator,
                                 uint80 _mintFeeNumerator,
                                 uint80 _mintFeeDenominator,
                                 uint256 _mintFeeFlat,
                                 uint80 _burnFeeNumerator,
                                 uint80 _burnFeeDenominator,
                                 uint256 _burnFeeFlat) public onlyOwner {
        require(_transferFeeDenominator != 0);
        require(_mintFeeDenominator != 0);
        require(_burnFeeDenominator != 0);
        transferFeeNumerator = _transferFeeNumerator;
        transferFeeDenominator = _transferFeeDenominator;
        mintFeeNumerator = _mintFeeNumerator;
        mintFeeDenominator = _mintFeeDenominator;
        mintFeeFlat = _mintFeeFlat;
        burnFeeNumerator = _burnFeeNumerator;
        burnFeeDenominator = _burnFeeDenominator;
        burnFeeFlat = _burnFeeFlat;
    }

    function changeStaker(address newStaker) public onlyOwner {
        require(newStaker != address(0));
        staker = newStaker;
    }
}