cxx20

We should add an example that demonstrates how to use a CUDA stream with thrust algorithms, e.g:

thrust::reduce(thrust::device.on(stream), ...);

I would like to be able to determine my device-wide primitive's temp_storage_bytes before I have all of the primitive's arguments ready. The interface for obtaining it ostensibly requires everything to be ready for the actual run - and the documentation does not make it clear what arguments it actually needs and what it's going to do with them (e.g. will it look at the input at all, in any way? Pr