How to get all securities in an asset class from IBPy (Interactive Brokers python API)

Would like to know how to request all securities in an asset class using IBpy, the python wrapper for the Interactive Brokers API.

For example getting all currency pairs in the class forex ('CASH'), or all stocks in the class equity ('STK').

Current efforts: Searched QF stack, stackoverflow and IBPy's google discussion groups. Ongoing efforts: Trawling through IBPy's "ibConection" class.

Thanks!