how i combine twin dictionaries unparalleled countenance python?

i have twin python dictionaries, i wish unparalleled countenance advantage twin dictionaries, merged. update() slight i need, returned the outcome instead modifying collection in-place.

>>> x = {'a': 1, 'b': 2}
>>> y = {'b': 10, 'c': 11}
>>> z = x.update(y)
>>> print(z)
none
>>> x
{'a': 1, 'b': 10, 'c': 11}

how i final assimilated collection z, x?

(to extra-clear, last-one-wins conflict-handling dict.update() i'm looking well.)