[boost] flyweight - gsoc idea - multikey-value flyweight

Hi Joaquin, I have a use case where I have several keys to the same flyweight. I was trying to associate a multi-index as factory, but I don't see how it could be done. I believe that I would need something like a multikey_value where KeyK should be deduced from KeyExtractorK. Have you found this use case already? Do you think this could be a good GSoC project? Best, Vicente