<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_asset_balance(self, asset, **params):
 """Get current asset balance. https://github.com/binance-exchange/binance-official-api-docs/blob/master/rest-api.md#account-information-user_data :param asset: required :type asset: str :param recvWindow: the number of milliseconds the request is valid for :type recvWindow: int :returns: dictionary or None if not found .. code-block:: python { "asset": "BTC", "free": "4723846.89208129", "locked": "0.00000000" } :raises: BinanceRequestException, BinanceAPIException """

        res = self.get_account(**params)
        # find asset balance in list of balances
        if "balances" in res:
            for bal in res['balances']:
                if bal['asset'].lower() == asset.lower():
                    return bal
        return None