Cryo Explorer Ethereum Mainnet

//
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//			                 Humans are overrated 
//							                  - Bubsy.ai
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// SPDX-License-Identifier: MIT

pragma solidity 0.8.20;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

interface IDEXFactory {
   function createPair(address tokenA, address tokenB) external returns (address pair);
}

interface IDEXRouter {
   function factory() external pure returns (address);
   function WETH() external pure returns (address);
   function swapExactTokensForETHSupportingFeeOnTransferTokens(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline) external;
}

interface IDEXReward {
   function updatePool() external payable;
   function contractStatus() external pure returns (bool);
   function isWhitelistForSendFund(address fundContract) external pure returns (bool);
}

contract Bubsy is ERC20, Ownable {
	address public pair;
	
	uint256 public buyFee;
	uint256 public sellFee;
	
	uint256 public swapThreshold;
	uint256 public rewardThreshold;
	uint256 public tokenLimitPerWallet;
	
	address[3] private treasury;
	uint256[4] private fundShare;
	
	bool private swapping;
	IDEXRouter public router;
	IDEXReward public reward;
	
	mapping(address => bool) public isWalletTaxFree;
	mapping(address => bool) public isLiquidityPair;
	mapping(address => bool) public isWalletExemptFromLimit;
	
	event BuyFeeUpdated(uint256 newFee);
	event SellFeeUpdated(uint256 newFee);
	event WalletExemptFromTokenLimit(address wallet, bool value);
	event SwapingThresholdUpdated(uint256 amount);
	event RewardThresholdUpdated(uint256 amount);
	event RewardAddressUpdated(IDEXReward newAddress);
	event ETHRescueFromContract(address receiver, uint256 ETH);
	event TokenPerWalletLimitUpdated(uint256 amount);
	event NewLiquidityPairUpdated(address pair, bool value);
	event WalletExemptFromFee(address wallet, bool value);
	event TreasuryWalletUpdated(address treasury1, address treasury2, address treasury3);
	event FundShareUpdated(uint256 rewardShare, uint256 treasury1Share, uint256 treasury2Share, uint256 treasury3Share);
	
    constructor(address _owner) ERC20("Bubsy AI", "BUBSY") {
	   require(_owner != address(0), "Owner:: zero address");
	   
	   router = IDEXRouter(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
       pair = IDEXFactory(router.factory()).createPair(address(this), router.WETH());
	   
	   treasury = [address(0x942b2c688cD5C20d33B8525c13472ca6a83670C0), address(0x5249c423FDB7D5a6eb74747A6baE11e4e8CCC70E), address(0x8a8dBA4Fcc1dF3D02C400c14DA4B7B97bc55A9c9)];
	   fundShare = [2000, 3000, 3000, 2000];
	   
	   buyFee = 500;
	   sellFee = 500;
	   
	   isLiquidityPair[address(pair)] = true;
	   
	   isWalletTaxFree[address(this)] = true;
	   isWalletTaxFree[address(_owner)] = true;
	   
	   isWalletExemptFromLimit[address(this)] = true;
	   isWalletExemptFromLimit[address(pair)] = true;
	   isWalletExemptFromLimit[address(_owner)] = true;
	   
	   rewardThreshold = 1 * 10**18;
	   swapThreshold = 10000 * (10**18);
	   tokenLimitPerWallet = 70000 * (10**18);
	   
       _mint(address(_owner), 70000000 * (10**18));
	   _transferOwnership(address(_owner));
    }
	
	receive() external payable {}
	
	function updateSellFee(uint256 newSellFee) external onlyOwner {
	   require(newSellFee <= 9000 , "Max fee limit reached for 'Sell'");
	   
	   sellFee = newSellFee;
	   emit SellFeeUpdated(newSellFee);
	}
	
	function updateBuyFee(uint256 newBuyFee) external onlyOwner {
	   require(newBuyFee <= 9000 , "Max fee limit reached for 'Buy'");
	   
	   buyFee = newBuyFee;
	   emit BuyFeeUpdated(newBuyFee);
	}
	
	function exemptWalletFromTokenLimit(address wallet, bool status) external onlyOwner {
	   require(wallet != address(0), "Zero address");
	   require(isWalletExemptFromLimit[wallet] != status, "Wallet is already the value of 'status'");
	   
	   isWalletExemptFromLimit[wallet] = status;
	   emit WalletExemptFromTokenLimit(wallet, status);
	}
	
	function exemptWalletFromFee(address wallet, bool status) external onlyOwner{
        require(wallet != address(0), "Zero address");
		require(isWalletTaxFree[wallet] != status, "Wallet is already the value of 'status'");
		
		isWalletTaxFree[wallet] = status;
        emit WalletExemptFromFee(wallet, status);
    }
	
	function updateSwappingThreshold(uint256 amount) external onlyOwner {
  	    require(amount <= totalSupply(), "Amount cannot be over the total supply.");
		require(amount >= (100 * 10**18), "Amount cannot be less than `100` token.");
		
		swapThreshold = amount;
		emit SwapingThresholdUpdated(amount);
  	}
	
	function updateRewardThreshold(uint256 amount) external onlyOwner {
		require(amount >= 0, "Amount cannot be zero");
		
		rewardThreshold = amount;
		emit RewardThresholdUpdated(amount);
  	}
	
	function updateLiquidityPair(address newPair, bool value) external onlyOwner {
        require(newPair != address(0), "Zero address");
		require(isLiquidityPair[newPair] != value, "Pair is already the value of 'value'");
		
        isLiquidityPair[newPair] = value;
        emit NewLiquidityPairUpdated(newPair, value);
    }
	
	function updateTokenLimitPerWallet(uint256 amount) external onlyOwner {
		require(amount <= totalSupply(), "Amount cannot be over the total supply.");
		require(amount >= 100 * (10**18), "Minimum `100` token per wallet required");
		
		tokenLimitPerWallet = amount;
		emit TokenPerWalletLimitUpdated(amount);
	}
	
	function updateTreasuryWallet(address[3] calldata newWallet) external onlyOwner {
		require(newWallet[0] != address(0) && newWallet[1] != address(0) && newWallet[2] != address(0), "Zero address");
		require(!isContract(newWallet[0]) && !isContract(newWallet[1]) && !isContract(newWallet[2]), "Contract address is not allowed");
		
		treasury[0] = address(newWallet[0]);
		treasury[1] = address(newWallet[1]);
		treasury[2] = address(newWallet[2]);
        emit TreasuryWalletUpdated(address(newWallet[0]), address(newWallet[1]), address(newWallet[2]));
    }
	
	function updateFundShare(uint256[4] calldata newShare) external onlyOwner {
		require(newShare[0] + newShare[1] + newShare[2] + newShare[3] == 10000, "Share is not correct");
		
		fundShare[0] = newShare[0];
		fundShare[1] = newShare[1];
		fundShare[2] = newShare[2];
		fundShare[3] = newShare[3];
        emit FundShareUpdated(newShare[0], newShare[1], newShare[2], newShare[3]);
    }
	
	function updateRewardAddress(IDEXReward newAddress) external onlyOwner {
	    require(address(newAddress) != address(0), "Zero address");
		
	    reward = IDEXReward(newAddress);
		isWalletTaxFree[address(reward)] = true;
		isWalletExemptFromLimit[address(reward)] = true;
	    emit RewardAddressUpdated(newAddress);
    }
	
	function rescueETH(address receiver, uint256 amount) external onlyOwner {
	   require(receiver != address(0), "Zero address");
	   require((address(this).balance) >= amount, "Insufficient ETH balance in contract");
	   
	   payable(address(receiver)).transfer(amount);
	   emit ETHRescueFromContract(address(receiver), amount);
    }
	
	function manualSendReward(uint256 amount) external onlyOwner {
	   require(address(this).balance >= amount, "Insufficient ETH balance in contract");
	   
	   if(isEligibleToDistributeReward())
	   {
		  reward.updatePool{value: amount}();
	   }
    }
	
	function isEligibleToDistributeReward() internal view returns(bool){
	   if(reward.contractStatus() && reward.isWhitelistForSendFund(address(this)) && address(reward) != address(0))
	   {
	       return true;
	   }
	   else
	   {
	       return false;
	   }
	}
	
	function _transfer(address sender, address recipient, uint256 amount) internal override(ERC20) {      
        require(sender != address(0), "transfer from the zero address");
        require(recipient != address(0), "transfer to the zero address");
		
		uint256 contractTokenBalance = balanceOf(address(this));
		bool canSwap = contractTokenBalance >= swapThreshold;
		
		if(!swapping && canSwap && isLiquidityPair[recipient]) 
		{
			swapping = true;
			
			uint256 oldBalance = address(this).balance;
			swapTokensForETH(swapThreshold);
			uint256 newBalance = (address(this).balance) - oldBalance;
			
			uint256 treasury1Share = ((newBalance * fundShare[1]) / 10000);
			uint256 treasury2Share = ((newBalance * fundShare[2]) / 10000);
			uint256 treasury3Share = ((newBalance * fundShare[3]) / 10000);
			
			if(treasury1Share > 0)
			{
			    payable(treasury[0]).transfer(treasury1Share);
			}
			if(treasury2Share > 0)
			{
			    payable(treasury[1]).transfer(treasury2Share);
			}
			if(treasury3Share > 0)
			{
			   payable(treasury[2]).transfer(treasury3Share);
			}
			if(isEligibleToDistributeReward() && address(this).balance >= rewardThreshold)
			{
			   reward.updatePool{value: address(this).balance}();
			}
			swapping = false; 
		}
		
		if(isWalletTaxFree[sender] || isWalletTaxFree[recipient])
		{
		    super._transfer(sender, recipient, amount);
		}
		else
		{
		    uint256 fees;
		    if(isLiquidityPair[recipient])
		    {
		        fees = ((amount * sellFee) / 10000);
		    }
		    else if(isLiquidityPair[sender] && recipient != address(router))
		    {
               fees = ((amount * buyFee) / 10000);	   
		    }
			
			if(!isWalletExemptFromLimit[recipient])
		    {
		       require(((balanceOf(recipient) + amount) - fees) <= tokenLimitPerWallet, "Transfer amount exceeds the `tokenLimitPerWallet`.");   
		    }
		    if(fees > 0) 
		    {
			   super._transfer(sender, address(this), fees);
		    }
		    super._transfer(sender, recipient, amount - fees);
		}
    }
	
	function swapTokensForETH(uint256 amount) private {
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = router.WETH();
		
        _approve(address(this), address(router), amount);
        router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            amount,
            0,
            path,
            address(this),
            block.timestamp
        );
    }
	
	function isContract(address account) internal view returns (bool) {
        return account.code.length > 0;
    }
}

// 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;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (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.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * 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}.
     *
     * The default value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * 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 value {ERC20} uses, unless this function is
     * 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;
        }
        _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;
        _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;
        }
        _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 {}
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (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);
}

// 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);
}