Function iter

code/other/two_sat.test.cpp:17–19

      TwoSat ts(n);
      iter(it,clauses) {
        ts.add_or(it->first, it->second);
      }
      if (ts.sat()) {
        vector<bool> is_true(n+1, false);
        // for (int i = 0; i < size(all_truthy); i++) if (all_truthy[i] > 0) is_true[all_truthy[i]] = true;