Hey @tramtran,

I didn't try with repos, but it works with a Workspace path the following way (we're doing it like this so I validated it for you). I guess since Repos are also inside /Workspace, it will work the same way. 

Lets use the default /Workspace/Shared folder for this example.

1. Add the .py file with your table_exists function to the /Workspace/Shared folder. Lets call the file function_file.py for this example. 
2. Create an __init__.py file in this/Workspace/Shared directory as well. So Databricks knows this is a package index. 
3. In the notebook you want to import the function from the .py file, add this:

import sys
sys.path.append("/Workspace/Shared")

then import the function like this:

from function_file import table_exists

Hope this helps, good luck!