old_contents: from Events import Events
  from BranchAddressManager import BranchAddressManager
  from Branch import Branch
  
  try:
      from BEvents import BEvents
      from BranchBuilder import BranchBuilder
      from BranchAddressManagerForVector import BranchAddressManagerForVector
  except ImportError:
      pass
  
new_contents: from Events import Events
  from BranchAddressManager import BranchAddressManager
  from Branch import Branch
  
  hasROOT = False
  try:
      import ROOT
      hasROOT = True
  except ImportError:
      pass
  
  if hasROOT:
      from BEvents import BEvents
      from BranchBuilder import BranchBuilder
      from BranchAddressManagerForVector import BranchAddressManagerForVector
  
subject: change the way to check if ROOT can be imported