#include <cassert>
#include <iostream>

namespace demo {
unsigned add(unsigned a, unsigned b);
}

int main() {
    const auto result = demo::add(2u, 3u);
    assert(result == 5u);
    assert(demo::add(0u, 7u) == 7u);
    std::cout << result << '\n';
}

namespace demo {
unsigned add(unsigned a, unsigned b) {
    return a + b;
}
}