Getting broker spread

Is there any function that can give me the difference between bid and ask? I know that price function is the ask, so only issue is how do I get the value for bid price.
Only thing I came across was BrokerAsset function, but that only checks if it is a specific number. I need to get the exact number.
Thanks

var Bid = priceClose()-Spread;

Thank you. I thought Spread was simulated only.