Differences between function "get_velocity_files" and "kb ref" command

[skpalan]

Hi, thanks for developing such a fantistic tool! I am new to kallito|bustool and currently trying to perform RNA velocity analysis on some spatial transcriptomic data. I noticed that there are two ways to build the reference index, which are either through the get_velocity_files function from BUSpaRse, or using kb ref.

However, what confuses me is there is a unique parameter L for get_velocity_files and it does not exist in the kb ref command. So what is the differences between using vs not using this parameter?