Performance of map vs starmap.

[Kirill Balunov]

Sometime ago I asked this question at SO [1], and among the responses
received was paragraph:

 - `zip` re-uses the returned `tuple` if it has a reference count of 1 when
the `__next__` call is made.
 - `map` build a new `tuple` that is passed to the mapped function every
time a `__next__` call is made.

Why can not `map` use the same approach as `zip`?

Also it turns out that a faster solution looks not reasonable, since it
requires additional calculations..

[1] https://stackoverflow.com/questions/46172018/perfomance-
of-map-vs-starmap

Thanks,
- gdg