#!/Users/victorelgersma/.pyenv/shims/python3
import os

folder = r"./"

for root, dirs, files in os.walk(folder):
    # Rename files
    for filename in files:
        if " " in filename:
            new_name = filename.replace(" ", "_")
            os.rename(os.path.join(root, filename), os.path.join(root, new_name))

    # Rename dirs (bottom-up would be safer, but os.walk topdown=True
    # means we rename dirs in-place and update dirs list so walk continues correctly)
    for i, dirname in enumerate(dirs):
        if " " in dirname:
            new_name = dirname.replace(" ", "_")
            os.rename(os.path.join(root, dirname), os.path.join(root, new_name))
            dirs[i] = new_name  # update so os.walk descends into the renamed dir