void test(){

  TH1D* unweighted = new TH1D("no weights","no weights",5,0,5);
  TH1D* weighted = new TH1D("weights","weights",5,0,5);

  unweighted->Fill(2);
  unweighted->Fill(3);
  unweighted->Fill(4);

  weighted->Fill(2);
  weighted->Fill(3,-1);
  weighted->Fill(4,-1);

  TCanvas *c1 = new TCanvas();
  c1->Divide(1,2);
  c1->cd(1);
  unweighted->Draw();
  c1->cd(2);
  weighted->Draw();


}