#include <vector>
#include <string>
#include <iostream>

std::vector<std::string> operator<<(std::vector<std::string>&& op, std::string str) 
{
    op.push_back(std::move(str));
    return op;
}

int main()
{
    std::vector<std::string> a = std::vector<std::string>() << "A" << "B";
    return 0;
}