# on Windows
import os
import pathlib 
parts = "\\\\", "host", "share", "whatever"
os.path.join(*parts)  # way 1, os.path is ntpath here
pathlib.Path(*parts)  # way 2, uses ntpath underneath
# None of these ways create a valid UNC. As a developer, I expect it to work the same as posixpath.join or have it documented why it doesn't