'Creates a Stop order.
A stop order, also referred to as a stop-loss order, is an order to buy or sell a stock once the price of the stock
reaches a specified price, known as the stop price.
When the stop price is reached, a stop order becomes a market order.
A buy stop order is entered at a stop price above the current market price. Investors generally use a buy stop order
to limit a loss or to protect a profit on a stock that they have sold short.
A sell stop order is entered at a stop price below the current market price. Investors generally use a sell stop order
to limit a loss or to protect a profit on a stock that they own.
:param action: The order action.
:type action: Order.Action.BUY, or Order.Action.BUY_TO_COVER, or Order.Action.SELL or Order.Action.SELL_SHORT.
:param instrument: Instrument identifier.
:type instrument: string.
:param stopPrice: The trigger price.
:type stopPrice: float
:param quantity: Order quantity.
:type quantity: int/float.
:rtype: A :class:`StopOrder` subclass.'

@abc.abstractmethod
def createStopOrder(self, action, instrument, stopPrice, quantity):

    raise NotImplementedError()
