hi all I'm new to creating my own setuptools projects, although I have work with other people projects before, so I'm not that lost here. but What I want to accomplish is having dependancies on some packages. for example my project will have diferent database backends so I want to depend on pysqlite or mysql-python depending on which the user wants as his/her backend. I'm going to have lots of diferent backends, even some that are not databases, so this will be a crutial thing for me or I'll end up with very big dist files per release, which will mostly be waste if the user never uses them. is something like this possible with setuptools now? is it plan to be possible in the future? if so any estimates on when will this be?