Can I do this in Bolt? (procedural generation patterns)

I'm trying to follow this tutorial and reproduce it in Bolt, but I got to the point that I don't think this is possible?

https://blogs.unity3d.com/2018/05/29/procedural-patterns-you-can-use-with-tilemaps-part-i/

I get kinda stuck at the  first block of code. I'm usually able to find some code and adapt it to Bolt, but this eludes me.

I added the type "array" to Bolt with the Unit Options wizard, so I can create an array that is for example 10x10 (using Array CreateInstance), I can get the size using get upper bound, but I don't know how to store both of them in a single variable?

I suppose next is a For each loop.

Another question,  X++. Is SUM the most convenient way to increase a value in Bolt?