Given a key, how do I read the value from a iterable table via the API?

Question

I have a struct like this:

struct MarketData {
markets: IterableTable\<u64, Data\>

,
whitelist: IterableTable\<address, address\>,
isOpenForAll: u64
}

Given a key, how do I read the value from an iterable table via the API?

I tried but got this error: