efficient way to convert SDDMM output to dense

[hadifar]

Thanks for releasing the code.
In your test API, I saw that you are using the Scipy api to convert the sparse output to the dense. However, I guess this is not an efficient way to convert it back. I would like to know, do you have any suggestion to make it more efficient? More precisely, I would like to know how I can get a dense output for SDDMM without sacrificing the performance?