void RootTutorial2() {

  cout << "[root_tutorial_2] Hello intern!" << endl;
  cout << "[root_tutorial_2] This Macro will walk you through looping a TTree and making your own plot." << endl;

  cout << "[root_tutorial_2] Reading ROOT file." << endl;
  TFile *f = new TFile("./zjet.root");

  cout << "[root_tutorial_2] Geting TTree from root file." << endl;
  TTree *t = (TTree*) f -> Get( "Tdata" );

  cout << "[root_tutorial_2] Declaring TH1D (your plot object)." << endl;
  TH1D *h = new TH1D( "h", "Z mass (GeV)", 100, 50, 150 );

  // These are the variables that will receive the data in the TTree
  vector<int> *id = 0;
  vector<double> *m = 0;

  // This is how you say to the TTree that these are the variables taking in the information
  t->SetBranchAddress("id",&id);
  t->SetBranchAddress("m",&m);

  // Now will make a for loop on the TTree entries
  cout << "[root_tutorial_2]  Looping on the TTree." << endl;
  for (int iEnt = 0; iEnt < t->GetEntries(); ++iEnt) {

    // This is how you get an entry from the TTree, i.e. this is how you load the values from a given entry to your variables
    t->GetEntry(iEnt);

    // We now loop on the objects of the event which are encoded in the vectors:
    for (int iObj = 0; iObj < (*id).size(); ++iObj) {

      // We want the Z boson, which in this case as id 0 (these id's are different from Pythia's)
      if ((*id)[iObj] == 0 ) h->Fill((*m)[iObj] , 1);
    }

  }

  // Now we wanna draw our object. You can create a TCanvas for this where you can control the width and the height, but for this demonstration it's not necessary
  cout << "[root_tutorial_2] Drawing your plot." << endl;
  h->Draw();

  cout << "[root_tutorial_2] Next macro you'll reconstruct the Z and the jet from particles a detector could find and try to write the objects to a file this macro can read." << endl;

}