os

os.path

# safe join of dirs & files
os.path.join(a, b)

# extract basename, dirname
os.path.basename(path) # a/b/c --> c
os.path.dirname(path) # a/b/c --> a/b

os.walk

# regular usage: find all files under path recursively
images = []
for root, dirs, files in os.walk(path):
    for f in files:
        if f.endwith('.png'):
            images.append(f)


# exclude directory while walking 
for root, dirs, files in os.walk(path):
    [dirs.remove(d) for d in list(dirs) if d in exclude_lists]
    ...