function int load_training_image(uint8 image[28][28], uint8* label, int idx) {
    if idx >= 60000 then return 0;
    *label = idx % 10;
    for i in 0..27, j in 0..27 {
        int val = (i > 8 && i < 20 && j > 8 && j < 20) ? 255 : 0;
        image[i][j] = val;
    }
    return 1;
}

void test_pointers(int** p) {
    int* q = *p;
    int r = **p;
}