store multiple images in a single file using sqlite3 in Python

allessandro.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
import glob
import os
import sqlite3

# support both Python 2.x and 3.x
try: buffer = buffer
except NameError:
    buffer = lambda x: x # on Python 3.x 'rb' mode already returns what we need

def U(literal_string):
    if hasattr(literal_string, 'decode'):
        return literal_string.decode('utf-8') # source code encoding
    return literal_string

# open db
conn = sqlite3.connect('images.db')
conn.execute('''create table if not exists images (
                    path unique not null, 
                    image blob
                )''')

def genimages():
    """Generate example images."""
    for pngpath in glob.iglob(os.path.expanduser(U('~/Pictures/*.png'))):
        with open(pngpath, 'rb') as f:
            yield pngpath, buffer(f.read())

# insert images
with conn: # insert all or nothing
    conn.executemany('insert into images(path,image) values(?, ?)', genimages())

# print image paths
for path, in conn.execute('select path from images'):
    print(path)