In Python, a function that makes and returns a copy would be idiomatically named shuffled(). Consider sorting:
xs.sort() # in-place
ys = sorted(xs) # copy
As for functions returning the object - I think it's a hack around the absence of direct support for such repetition in the language itself. E.g. in Object Pascal, you'd write:
with array do
begin
append(A);
append(B);
sort;
end;
