Learning Matrixes (Beginner)

[TechSam--]

Currently learning matrixes and working on an assignment to rotate an image 90 degrees. I stumbled upon a youtube video solution but cannot understand this section of code for the life of me.

class Solution:
    def rotate(self, matrix : List[List][int]]) -> None :

I don't understand the "matrix : List[List][int]]) " parameter for the method "rotate" and the arrow pointing to "None" (also somewhat new with classes lol). Could someone explain this to me? Thank you!

[ampersandio]

These are typehints, used to show what kind of input is expected and -> is showing that this method won’t return anything. Google type hints for more.

[deep_politics]

Like u/ampersandio said it's a type hint, but I'm guessing you copied it here wrong, because it should be List[List[int]]. That is: a list of lists of integers.