What does "#type: " mean?

    def max(self, list_in):
        # type: (List[List[int]]) -> List[int]
        maxes = the_list[0]
        for sublist in list_in[1:]:
            for index, item in enumerate(sublist):
                maxes[index] = max(maxes[index], item)
        return maxes

In this func , if i dont follow the rule (input dtype is List[List[int]] & output type is List[int]),but nothing happened … so what’s the meaning of “# type”?

it’s just a comment to make you understand what are the types of the input and output