@property
def sell_margin(self):
    '\n        [float] 卖方向持仓保证金\n        '
    return (self._sell_holding_cost * self.margin_rate)
[float] 卖方向持仓保证金
@property
def sell_margin(self):
    '\n        \n        '
    return (self._sell_holding_cost * self.margin_rate)