I normally use notebooks in a `notebooks` sub path in my project repository and often need to import modules that are apart of that project.

jupyter-notebook-starter.py

import sys
sys.path.append("../") # go to parent dir
from customFunctions import *

# Then, to affect changes in customFunctions.py,
%load_ext autoreload
%autoreload 2

#ref: https://stackoverflow.com/a/42727538/23991