// In some languages, you can do this
// USAGE
for enemy_iterator() {
    // do things with enemy
    enemy.name = "clown";
}

// IMPLEMENTATION
enemy_iterator()
{
    chunks = get_chunks(...)
    for each chunk {
        for each enemy in chunk {
            yield; // this basically pastes the enemy.name = "clown"; in here
        }
    }
}

// ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
// To do this in C, you can do something like this (kinda cringe)
// USAGE
EnemyIterator iterator = {};
while(enemy_iterator(&iterator)) {
    iterator.enemy.name = "clown";
}

// IMPLEMENTATION
bool enemy_iterator(EnemyIterator* iterator)
{
    chunks = get_chunks(...);
    for(int i = iterator->chunk_index; i < chunk_count; i += 1) {
        Chunk chunk = chunks[i];
        iterator->chunk_index += 1;
        for(int j = iterator->enemy_index; j < chunk.enemy_count; j += 1) {
            iterator->enemy_index += 1;
            Enemy* enemy = chunk.enemies[j];
            iterator->enemy = enemy;
            return true;
        }
    }
    return false;
}