tell me please, what happend, when come liquidation process? user A put 1000usdt to Support user B put X btc to Support and turn on it as Collateral in dashboard user B borrow 1000usdt using btc as collateral and lost it (drink beer for example) 1. no any liquidation process, btc price infinitely rised up 2. a liquidation process happened, btc price dropped down (so collaterated btc price below 1000usdt price) how user A give back usdt? hi got btc?