通过迭代器访问另一个向量内的向量元素？

#include<iostream>
#include<vector>

int main() {
    std::vector<std::vector<int>> vec = {{1, 2}, {3, 4}, {5, 6}};

    for (auto it1 = vec.begin(); it1 != vec.end(); ++it1) {
        for (auto it2 = it1->begin(); it2 != it1->end(); ++it2) {
            std::cout << *it2 << " ";
        }
    }

    return 0;
}

vec = [[1, 2], [3, 4], [5, 6]]

for inner_vec in vec:
    for element in inner_vec:
        print(element, end=" ")