#include <vector>
#include <iterator>
#include <iostream>

using namespace std;

vector<int>& operator+=(vector<int>& v, int x) {
	for (auto a=begin(v); a!=end(v); ++a) {
		*a += x;
	}
	return v;
}

int main() {
	vector<int> a = {1, 2, 3};
	a += 10;
	copy(begin(a), end(a), ostream_iterator<int>(cout, ", "));
}