Feature request: return-trip or multi-city

[aerospeace]

Good afternoon,

Thanks a lot for this amazing project.
Would it be possible for you to implement fetching data for return trip or multi-city?
Indeed, international flights over the Atlantic have a highly difference price depending on whether we book the return flight with original flight or not.
I would have loved to help, but the code is way above my skill set!

Thank you!