import pickle

output = open('testpickle', 'w')

p = pickle.Pickler(output)
x = {1:2}
p.dump(x)
x[2] = 3
p.dump(x)

output.close()

u = pickle.Unpickler(open('testpickle'))

print u.load()
print u.load()

# output:
# {1: 2}
# {1: 2}