Never saw this kind of code

Question

Did u ever see a kind of line 3 and 4 of that code?
What is its use?
https://code.sololearn.com/ca0ZTgBMDthE/?ref=app

Answer 1

It's a type annotation. It does not influence the running code but it can be good for the programmer reading that code.
Some IDEs and static analyzers like mypy can use them to give you auto-suggestions and find errors.
You usually put them to function declarations
def sum (a: int, b: int) -> int:
but you can annotate any variable. This is useful for example for empty lists
arr: List[int] = []
where you cannot guess the type from the value

Answer 2

https://stackoverflow.com/questions/51639332/use-of-colon-in-variable-declaration

Answer 3

it just annotation..u can think as type hint..but i think it doesnt mean python support static type

Answer 4

:int seems to be unnecessary. The code runs fine without them.

Answer 5

David Ashton yes. Maybe you want read this article too
https://stackoverflow.com/questions/51639332/use-of-colon-in-variable-declaration

Answer 6

Frogged / David Ashton this is actually old but rewritten trick originally created via Perl under the disguise of labelling passed to Python somewhere around 3.6

Answer 7

Jan Markus 😂👍

Answer 8

That is just an annotation. If you want to use static typing in python, then you might have a look at this, Pure Python mode in Cython | https://cython.readthedocs.io/en/latest/src/tutorial/pure.html

Answer 9

Js Aakash yes but the question as it relates to the topic is about specifically lines 3 and 4 where a label eg last and next are being used and identified as integers int which is not common use in python as Frogged was pointing out in her question.

I did a very minor addition to her code

https://code.sololearn.com/coHekpyZ6YN8/?ref=app

Answer 10

Like declaring a,b=0,1? maybe

Answer 11

again a typical Guido...

Answer 12

Mirielle yes only an annotation

Answer 13

Is it recursion

Answer 14

It looks like defining the variable type like we do un typescript
>>> let a : string;

Answer 15

https://www.geeksforgeeks.org/top-10-JUMP_LINK__&&__python__&&__JUMP_LINK-ide-and-code-editors-in-2020/

Answer 16

Krish [less active] its not actually defining the variable type, rather its a virtual communication between the programmers and the IDEs.

Answer 17

Faheem

Then even it's for defining the type for the ide 😂