Get Market Spot Price

Function Get Market Spot Price within
Tradable returns the default spot price under which the supplied tradable is supposedly traded, before it is overriden by any user-supplied market data.
If a real time data provider exists, then this will be just the price delivered by that provider.
On the absence of such a provider, a fixed value is returned, which is not the result of a calculation.
Note this value is used in the initial construction by Deriscope of relevant default market data.