lst-0065-book.cpp
// https://godbolt.org/z/9b9fY4Mve
#include <iostream>
#include <forward_list>
int main() {
std::forward_list mylist = {20, 30, 40, 50};
mylist.insert_after(mylist.before_begin(), 11 );
for (int& x: mylist) std::cout << ' ' << x; // Output: 11 20 30 40 50
std::cout << '\n';
}