{
   int  v_i = 0;

   TFile *hfile = hfile = TFile::Open("o.root","RECREATE", "", 207);

   TTree *tree = new TTree("T","data for rust tests");
   tree->Branch("v_i",&v_i);
   
   for (int i = -10; i < 10; ++i)
     {
       v_i = i;
       tree->Fill(); 
     }   

   tree->Print();
   tree->Write();   
   delete hfile;
}