[boost] [Fusion] Feature Request: flat_view

I have a request for a new type of view for the fusion library: flat_view. This would operate on sequences that contain other sequences, for instance tuple<double, tuple<int, long>, pair<double, string> > and flatten them by recursively digging into the contained sequences to get all of their types. So for the example above, it's size would equal 5 and it's returned types would be double, int, long, double, string. I don't know how difficult this would be to implement, but I think it could be very useful. Joe Gottman