There are many places where we could make use of Pathlib.

Look for any places that uses with open(...) and ask yourself:

• is the argument a string ?
• would it make sens to make it a Path(),
• how far upstream in the code can I make it a Path.

Don't try to bite more than you can chew (or more than I can review), try to fix 1 place at a time.

/kind feature

This is a sub-issue from #5494.
We need to remove any f"strings" from the backend of the Jupyter web app in order to be able to use lower versions from Python 3.6 to run it.

/good-first-issue

Hello,

Make image tags consistent

The images will be tagged as described below

• base-notebook:
  • SHA: Commit short SHA
  • python-$VER: Python version
  • notebook-$VER: Jupyter Notebook version
  • lab-$VER: JupyterLab version
  • hub-$VER: JupyterHub version
• minimal-notebook:
  • all upstream tags
• scipy-notebook:
  • all upstream tags
• `r-no

The plotting UI leaves a lot to be desired:

• When you bring up the plotting UI, it's not obvious that you have to do some work to make a plot happen. If you don't, there's no error message, just a never-ending wait. (see https://gitter.im/polynote/polynote?at=5e0e36f9eac8d1511e9ed2ff )
• Why do we make you drag things onto axes? Especially when there is only one axis it could go onto (at leas

Use case

Polyaxon tracking can be used to automatically log all information generated by Ludwig.

We should probably think about adding support for Polyaxon's tracking module in Ludwig contrib.

I was trying to save a Pluto notebook in a path that doesn't exist. This is how the directory looked before:

Now I wanted to create a new submission sub-directory inside the julia directory and save the file there.

![image](https://user-images.githubusercontent.com/28949397/