Adding a custom Python library path in a Jupyter Notebook

This code adds a Python library path relative to your working folder to enable you to load custom library functions from a Jupyter Notebook:

import sys, os
extra_path = os.path.join(os.getcwd(), "lib")
if extra_path not in sys.path:
    sys.path.append(extra_path)
    print('Added extra_path:', extra_path)

Then import like so:
import <my_file_name_in_lib_folder> as funcs

If in a Jupyter Notebook with Python 3.4+ the following will automatically reload the library:
import importlib
importlib.reload(funcs)