When opening a transaction in futures via mexc api, I cannot determine the vol value, that is, the amount we want to receive, when I write 0.2 directly, “{‘success’: False, ‘code’: 2015, ‘message’: ‘Price or amount precision error!’}” error, but when I open a transaction of 0.2 amount myself via mexc, it says 2 on the api, I need a code that automatically calculates this value.