// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

// https://github.com/OpenZeppelin/openzeppelin-contracts/blob/5daaf60d11ee2075260d0f3adfb22b1c536db983/contracts/token/ERC20/StandardBurnableToken.sol
// implementation: https://gnosisscan.io/address/0xf8d1677c8a0c961938bf2f9adc3f3cfda759a9d9#code
// proxy: https://gnosisscan.io/token/0x6a023ccd1ff6f2045c3309768ead9e68f978f6e1#readProxyContract

/**
 * @title Standard Burnable Token
 * @dev Token that can be irreversibly burned (destroyed).
 */
interface IWETH {
    /**
     * @dev Burns a specific amount of tokens.
     * @param _value The amount of token to be burned.
     */
    function burn(uint256 _value) external;

    /**
     * @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) external view returns (uint256);

    /**
     * @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) external returns (bool);

    /**
     * @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) external returns (bool);

    /**
     * @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) external view returns (uint256);

    /**
     * @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) external returns (bool);
}