Okay, I did it.

    import subprocess
    import re
    import yaml

    output = subprocess.check_output(['ls', '-l'], universal_newlines=True)
    matching_lines = []

    for line in output.splitlines():
        if re.search(r'total', line):
            matching_lines.append(line)

    with open('matching_lines.yaml', 'w') as f:
        f.write(yaml.dump(matching_lines))

Python 3.7: https://repl.it/repls/PotableDamagedAutocad

Python 2.7: https://repl.it/repls/OrchidDirtyNotification