This guide shows you how to add separators to plank.
Open the terminal and copy/paste the following;
sudo apt install git
git clone git://github.com/bipolarizm/PlankZer.git ~/PlankZer
cd ~/PlankZer
chmod +x plankzer.sh && ./plankzer.sh
If you want more than one separator, run the plankzer.sh script once more.
Enjoy! ^_^
Tested on: elementary OS 5.1.6
Tips and Guides for elementary OS 
Great. Already implemented locally. Thank you very much!
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