Using SsviVolatilityFunction Example

Hi all,

I would to build a tool to calibrate the vol surface of FX Option using SsviVolatilityFunction, is there an example on how to use it for that purpose? Also, any reason why phi would be phi = eta / Math.sqrt(theta) ?
Does the library also implemented the Interpolation and extrapolation in section 5 of the paper?

Thank you very much!