How to use the broker.Order.Action.BUY_TO_COVER function in broker

def onOrderEvent(self, broker_, orderEvent):
        order = orderEvent.getOrder()
        if self.__plotBuySell and orderEvent.getEventType() in (broker.OrderEvent.Type.PARTIALLY_FILLED, broker.OrderEvent.Type.FILLED) and order.getInstrument() == self.__instrument:
            action = order.getAction()
            execInfo = orderEvent.getEventInfo()
            if action in [broker.Order.Action.BUY, broker.Order.Action.BUY_TO_COVER]:
                self.getSeries("Buy", BuyMarker).addValue(execInfo.getDateTime(), execInfo.getPrice())
            elif action in [broker.Order.Action.SELL, broker.Order.Action.SELL_SHORT]:
                self.getSeries("Sell", SellMarker).addValue(execInfo.getDateTime(), execInfo.getPrice())

def onOrderUpdated(self, broker_, order):
		if self.__plotBuySell and order.isFilled() and order.getInstrument() == self.__instrument:
			action = order.getAction()
			execInfo = order.getExecutionInfo()
			if action in [broker.Order.Action.BUY, broker.Order.Action.BUY_TO_COVER]:
				self.getSeries("Buy", BuyMarker).addValue(execInfo.getDateTime(), execInfo.getPrice())
			elif action in [broker.Order.Action.SELL, broker.Order.Action.SELL_SHORT]:
				self.getSeries("Sell", SellMarker).addValue(execInfo.getDateTime(), execInfo.getPrice())

def buildExitOrder(self, limitPrice, stopPrice):
		if limitPrice == None and stopPrice == None:
			ret = self.getStrategy().getBroker().createMarketOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), self.getQuantity(), False)
		elif limitPrice != None and stopPrice == None:
			ret = self.getStrategy().getBroker().createLimitOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), limitPrice, self.getQuantity())
		elif limitPrice == None and stopPrice != None:
			ret = self.getStrategy().getBroker().createStopOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), stopPrice, self.getQuantity())
		elif limitPrice != None and stopPrice != None:
			ret = self.getStrategy().getBroker().createStopLimitOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), stopPrice, limitPrice, self.getQuantity())
		else:
			assert(False)

		return ret

def buildExitOrder(self, limitPrice, stopPrice):
		if limitPrice == None and stopPrice == None:
			ret = self.getStrategy().getBroker().createMarketOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), self.getQuantity(), False)
		elif limitPrice != None and stopPrice == None:
			ret = self.getStrategy().getBroker().createLimitOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), limitPrice, self.getQuantity())
		elif limitPrice == None and stopPrice != None:
			ret = self.getStrategy().getBroker().createStopOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), stopPrice, self.getQuantity())
		elif limitPrice != None and stopPrice != None:
			ret = self.getStrategy().getBroker().createStopLimitOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), stopPrice, limitPrice, self.getQuantity())
		else:
			assert(False)

		return ret

def buildExitOrder(self, limitPrice, stopPrice):
		if limitPrice == None and stopPrice == None:
			ret = self.getStrategy().getBroker().createMarketOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), self.getQuantity(), False)
		elif limitPrice != None and stopPrice == None:
			ret = self.getStrategy().getBroker().createLimitOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), limitPrice, self.getQuantity())
		elif limitPrice == None and stopPrice != None:
			ret = self.getStrategy().getBroker().createStopOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), stopPrice, self.getQuantity())
		elif limitPrice != None and stopPrice != None:
			ret = self.getStrategy().getBroker().createStopLimitOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), stopPrice, limitPrice, self.getQuantity())
		else:
			assert(False)

		return ret

def buildExitOrder(self, limitPrice, stopPrice):
		if limitPrice == None and stopPrice == None:
			ret = self.getStrategy().getBroker().createMarketOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), self.getQuantity(), False)
		elif limitPrice != None and stopPrice == None:
			ret = self.getStrategy().getBroker().createLimitOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), limitPrice, self.getQuantity())
		elif limitPrice == None and stopPrice != None:
			ret = self.getStrategy().getBroker().createStopOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), stopPrice, self.getQuantity())
		elif limitPrice != None and stopPrice != None:
			ret = self.getStrategy().getBroker().createStopLimitOrder(broker.Order.Action.BUY_TO_COVER, self.getInstrument(), stopPrice, limitPrice, self.getQuantity())
		else:
			assert(False)

		return ret