2013-04-18: Port number for TWS clients is no longer optional. 2013-04-16: Added a new interface Twsable. A type is 'Twsable' if it provides functions to convert between values of that type and raw messages of the TWS protocol. 2013-04-04: Fixed version mismatch in option price and implied volatility request. 2013-04-02: Initial public release.