[KEP] Allow using let to define local variable in "legacy for loop" like Javascript

[anzhi0708]

I can't find suitable title... so I'll go with 'KEP' (Kuroko Enhancement Proposal) lol

Using var defines global and let defines local variable in nodeJS (for loop)

They act differently.

Well, just personal thoughts though ;-)

[anzhi0708]

Before:

for _ in range(5):
    let i = _       # catch the value
    ...             # do stuff

After:

for let i = 0; i < 5; i++:  # init local variable i
    ...  # do stuff

...or even...

for let i in range(5):
    ...

[klange]

I don't want to use issues for enhancement proposals, so I've turned on Discussions - one of the default categories is "Ideas", let's put this sort of thing there.

(Also I really have to resist the urge to come up with an alternative to "proposal" that starts with "k" so we can have "KEKs"... good thing I can't find a sensible one...)