How to find a list of Futures Contracts for Currency Futures

[Red1n]

Question #115 provides a good framework for finding Futures and Futures Option contracts which works for NG, ES and others.

When I apply the same approach for Currency Futures, eg JPY or EUR using:

contract = Index("JPY", exchange="CME", currency="USD")
ib.qualifyContracts(contract)

Gives the error messge: Unknown contract: Index(symbol='JPY', exchange='CME', currency='USD')

and

contract = Future("JPY", exchange="CME", currency="USD")

Gives an Ambiguous Contract error as expected with a list of contracts in the error message as expected.

How do you find the underlying list of contracts for currency futures to determine the options chain?