[Python-Dev] What if replacing items in a dictionary returns the new dictionary?

It would be convenient if replacing items in a dictionary returns the new dictionary, in a manner analogous to str.replace(). What do you think? :: # Current behavior x = {'key1': 1} x.update(key1=3) == None x == {'key1': 3} # Original variable has changed # Possible behavior x = {'key1': 1} x.replace(key1=3) == {'key1': 3} x == {'key1': 1} # Original variable is unchanged