def sell(self, price: float, volume: float, stop: bool=False, lock: bool=False, vt_symbol: str='', order_type: OrderType=OrderType.LIMIT, order_time: datetime=None, grid: CtaGrid=None):
    '\n        Send sell order to close a long position.\n        '
    if (order_type in [OrderType.FAK, OrderType.FOK]):
        if self.is_lower_limit(vt_symbol):
            self.write_error(u'跌停价不做FAK/FOK sell委托')
            return []
    if (volume == 0):
        self.write_error(f'委托数量有误，必须大于0，{vt_symbol}, price:{price}')
        return []
    return self.send_order(vt_symbol=vt_symbol, direction=Direction.SHORT, offset=Offset.CLOSE, price=price, volume=volume, stop=stop, lock=lock, order_type=order_type, order_time=order_time, grid=grid)
Send sell order to close a long position.
def sell(self, price: float, volume: float, stop: bool=False, lock: bool=False, vt_symbol: str=, order_type: OrderType=OrderType.LIMIT, order_time: datetime=None, grid: CtaGrid=None):
    '\n        \n        '
    if (order_type in [OrderType.FAK, OrderType.FOK]):
        if self.is_lower_limit(vt_symbol):
            self.write_error(u'跌停价不做FAK/FOK sell委托')
            return []
    if (volume == 0):
        self.write_error(f'委托数量有误，必须大于0，{vt_symbol}, price:{price}')
        return []
    return self.send_order(vt_symbol=vt_symbol, direction=Direction.SHORT, offset=Offset.CLOSE, price=price, volume=volume, stop=stop, lock=lock, order_type=order_type, order_time=order_time, grid=grid)