Advanced Requires Clauses

#include <concepts>
#include <iostream>
#include <vector>
#include <string>
// Compound requirements
template<typename T>
concept Printable = requires(T t, std::ostream& os) {
    { os << t } -> std::same_as<std::ostream&>;
};
// Nested requirements
template<typename Container>
concept PrintableContainer = requires(Container c) {
    { c.begin() } -> std::input_or_output_iterator;
    { c.end() } -> std::input_or_output_iterator;
    requires Printable<decltype(*c.begin())>;
};
template<PrintableContainer C>
void print_all(const C& container) {
    for (const auto& item : container) {
        std::cout << item << " ";
    }
    std::cout << std::endl;
}
int main() {
    std::vector<int> nums = {1, 2, 3, 4, 5};
    std::vector<std::string> words = {"hello", "world"};
    
    print_all(nums);    // 1 2 3 4 5
    print_all(words);   // hello world
    return 0;
}