So far I am using Tkinter to make textfields in Python. 
My question is how do I make it so there are placeholders, preferably in the style of mathematica or something similar so that when a user starts a new line, a right and left place holder appear on that line and the user can only enter text in these placeholders? Eventually I would like to be able to make it so all the right placeholders are aligned as well, but that may be too complicated. I can't seem to find a way to do this in Tkinter. Is there possibly a better package for this?
I'm not sure how to generate and format "text placeholders"
Edit: I think this question is coming down to: how do I dynamically add text placeholders within already existing text fields based on certain key commands?
tkinter doesn't have anything built-in to support this. Tkinter likely has all of the fundamental building blocks in order to build it yourself, but it will require a lot of work on your part.
Adding dotted text placeholders within a textfield in Python?