'arr' in rand_by_mask function (lesson1.ipynb)

Hi everyone,
Just reinstalled everything on a local machine, and now I’m getting an error when running the rand_by_mask() function, because I don’t have the ‘arr’ symbol.

I’m seeing some recent changes in the git repository, don’t know if that’s related. For the moment, I removed the min(len(arr), 4) call and set it to 4 directly, as it was before, so I can continue running the lesson.

Does anybody know if this is the proper course of action?

Thanks in advance,