Simply backpack and use with credit! Supports empty and 1-character separators. Will not work with 2 or more characters. Want to see this become a real Scratch block, that can support multiple-character separators? Support it here: https://scratch.mit.edu/discuss/topic/124012/
See inside to play around with it! I had to hack the JSON to get the list functions to work. Let me know of any errors. Entering "OhiO" with separator "O" is supposed to give 2 empty items. I've tried to make this work exactly like it does in Python. By the way, I see a lot of hacked blocks projects that have the Scratch Cat as the one sprite, so I'm using Gobo.