get random pictures, save the state

from pathlib import Path
from random import choice
import pickle


def load_state():
    state_file = Path('state.json')
    if not state_file.exists():
        pictures = list(Path('.').glob('**/*.jpg'))
        save_state(pictures)
        return pictures
    else:
        with state_file.open('rb') as fd:
            return pickle.load(fd)


def save_state(pictures):
    state_file = Path('state.json')
    with state_file.open('wb') as fd:
        pickle.dump(pictures, fd)


def pop_random_picture(pictures):
    """
    This function mutates pictures.
    It returns a random picture from the set
    and removes this picture from the set.
    """
    if pictures:
        picture = choice(pictures)
        pictures.remove(picture)
        return picture
    return None


pictures = load_state()
print(f'Number of pics: {len(pictures)}')
print(pop_random_picture(pictures))
save_state(pictures)