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

[Roy Hyunjin Han]

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