}
// check if l2 contains a majority of the elements of l1
-bool majority(const nodes_t &l1, const nodes_t &l2) {
+bool majority(const nodes_t & l1, const nodes_t & l2) {
auto overlap = (size_t)count_if(l1.begin(), l1.end(), std::bind(isamember, _1, l2));
return overlap >= (l1.size() >> 1) + 1;
}