Python script to clean up some markdown files and turn a string into a list

string_to_list.py

# I had a bunch of markdown files in my blog that had a category value that was a string of words instead of a list
# I needed a way to parse and replace 40 lines that began with `categories:` at once
# This did it.

import re
import glob

# https://stackoverflow.com/questions/4568580/python-glob-multiple-filetypes
types = ('*.md') 
files_grabbed = []
for files in types:
    files_grabbed.extend(glob.glob(files))

for file in files_grabbed:
    with open(file, 'r') as f:
        content = f.readlines()
    content2 = ""
    for line in content:
        if line.startswith('categories: '):
            line = re.sub(r'\s', ', ', line)
            line = re.sub(r':, ', ': [', line)
            line = re.sub(', ,', ',', line)
            line = re.sub(', $', ']\n', line)
        content2 += line
    print(content2)
    with open(file, 'w') as f:
        f.write(content2)