int rootTest() {
  TFile* outfile = new TFile("test.root", "RECREATE");
  TTree* tree = new TTree("tree", "test tree");
  int bufsize = 32000;
  int split = 1;
  TwoVector* twoVec = new TwoVector(1,1);
  TBranch* b = tree->Branch("twoVec", "TwoVector", &twoVec, bufsize, split);

//  Fill with some random numbers.  

  for (int i = 0; i<100; ++i){
    float r1 = static_cast<float>(rand()) / static_cast<float>(RAND_MAX);
    float r2 = static_cast<float>(rand()) / static_cast<float>(RAND_MAX);
    twoVec->set(r1, r2);
    tree->Fill();
  }

  tree->Write();
  return 0;
}