contract ERC20Burnable is ERC20, Ownable {

    event Burn(address indexed owner, uint256 amount);

    /**
     * @dev Burn a specific amount of tokens.
     * @param _value The amount of token to be burned.
     */
    function burn(uint256 _value) public onlyOwner {
        require(_value <= _balances[msg.sender], "ERC20Burnable: not enough token balance");
        // 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

        _balances[msg.sender] = _balances[msg.sender].sub(_value);
        _totalSupply = _totalSupply.sub(_value);
        emit Burn(msg.sender, _value);
        emit Transfer(msg.sender, address(0), _value);
    }
}
/**
 * @title ERC20Burnable
 * Implement the function of ERC20 token burning.
 */
function burn(uint256 _value) public onlyOwner {
    require(_value <= _balances[msg.sender], "ERC20Burnable: not enough token balance");
    // 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

    _balances[msg.sender] = _balances[msg.sender].sub(_value);
    _totalSupply = _totalSupply.sub(_value);
    emit Burn(msg.sender, _value);
    emit Transfer(msg.sender, address(0), _value);
}

/**
 * @dev Burn a specific amount of tokens.
 * @param _value The amount of token to be burned.
 */