@property
def buy_margin(self):
    '\n        [float] 买方向持仓保证金\n        '
    return (self._buy_holding_cost * self.margin_rate)
[float] 买方向持仓保证金
@property
def buy_margin(self):
    '\n        \n        '
    return (self._buy_holding_cost * self.margin_rate)