shelve_test.py

import shelve

s = shelve.open('test_shelf')
try:
    print s['key1']
    value_for_key1 = s['key1']
    value_for_key1['new_value'] = 'this was not here before'
    
    s['key1'] = value_for_key1
finally:
    s.close()

s = shelve.open('test_shelf.db', writeback=True)
try:
    print s['key1']
finally:
    s.close()