contract ERC20Burnable is ERC20 {
    /**
     * @dev Destroys tokens from the owner account
     * @param amount Amount of tokens to be destroyed and subtracted from `totalSupply`
     */
    function burn(uint256 amount) public {
        _burn(msg.sender, amount);
    }
}
function burn(uint256 amount) public {
    _burn(msg.sender, amount);
}

/**
 * @dev Destroys tokens from the owner account
 * @param amount Amount of tokens to be destroyed and subtracted from `totalSupply`
 */