new_contents: #!/usr/bin/env python
  # Tai Sakuma <tai.sakuma@cern.ch>
  
  ##__________________________________________________________________||
  import os, sys
  import timeit
  import array
  import ROOT
  
  from alphatwirl.events import Events, BEvents
  
  # https://cp3.irmp.ucl.ac.be/projects/delphes/ticket/1039
  ROOT.gInterpreter.Declare('#include "classes/DelphesClasses.h"')
  ROOT.gInterpreter.Declare('#include "external/ExRootAnalysis/ExRootTreeReader.h"')
  ROOT.gSystem.Load("libDelphes.so")
  
  ##__________________________________________________________________||
  inputPath = '/hdfs/user/ds13962/delphes_jobs/job_20170417_001/QCD_HT1000to1500/0000/delphes.root'
  treeName = 'Delphes'
  
  ##__________________________________________________________________||
  def use_Events():
      inputFile = ROOT.TFile.Open(inputPath)
      tree = inputFile.Get(treeName)
      events = Events(tree)
      for event in events:
          for i in range(event.Jet.GetEntries()):
              event.Jet[i].PT
  
  ##__________________________________________________________________||
  def use_Events_SetBranchStatus_var():
      inputFile = ROOT.TFile.Open(inputPath)
      tree = inputFile.Get(treeName)
      tree.SetBranchStatus("*", 0)
      tree.SetBranchStatus("Jet.PT", 1)
      events = Events(tree)
      for event in events:
          for i in range(event.Jet.GetEntries()):
              event.Jet[i].PT
  
  ##__________________________________________________________________||
  def use_Events_SetBranchStatus_obj():
      inputFile = ROOT.TFile.Open(inputPath)
      tree = inputFile.Get(treeName)
      tree.SetBranchStatus("*", 0)
      tree.SetBranchStatus("Jet.*", 1)
      events = Events(tree)
      for event in events:
          for i in range(event.Jet.GetEntries()):
              event.Jet[i].PT
  
  ##__________________________________________________________________||
  # https://github.com/delphes/delphes/blob/master/examples/Example1.py
  def use_ExRootTreeReader():
      inputFile = ROOT.TFile.Open(inputPath)
      tree = inputFile.Get(treeName)
      treeReader = ROOT.ExRootTreeReader(tree)
      nentries = treeReader.GetEntries()
      branchJet = treeReader.UseBranch("Jet")
      for ientry in range(nentries):
          treeReader.ReadEntry(ientry)
          for i in range(branchJet.GetEntries()):
              branchJet[i].PT
  
  ##__________________________________________________________________||
  ways = [
      'use_Events',
      'use_Events_SetBranchStatus_var',
      'use_Events_SetBranchStatus_obj',
      'use_ExRootTreeReader'
  ]
  
  for w in ways:
      print w, ':',
      print timeit.timeit(w + '()', number = 1, setup = 'from __main__ import ' + w)
  
  ##__________________________________________________________________||
  # use_Events : 4.99250912666
  # use_Events_SetBranchStatus_var : 0.321241855621
  # use_Events_SetBranchStatus_obj : 0.540351867676
  # use_ExRootTreeReader : 0.495839118958
  
  ##__________________________________________________________________||
  
subject: add a new test file performance_Delphes.py