new_contents: ## \file
  ## \ingroup tutorial_dataframe
  ## \notebook
  ## Get information about the dataframe with the convenience method Describe.
  ##
  ## \macro_code
  ## \macro_output
  ##
  ## \date March 2021
  ## \author Stefan Wunsch (KIT, CERN)
  
  import ROOT
  
  # Create a dataframe
  path = 'root://eospublic.cern.ch//eos/opendata/cms/derived-data/AOD2NanoAODOutreachTool/Run2012BC_DoubleMuParked_Muons.root'
  df = ROOT.RDataFrame('Events', path)
  
  # Describe the state of the dataframe.
  # Note that this operation is not running the event loop.
  print(df.Describe())
  
  # Build a small analysis studying the invariant mass of dimuon systems.
  # See tutorial df102_NanoAODDimuonAnalysis for more information.
  df = df.Filter('nMuon == 2')\
         .Filter('Muon_charge[0] != Muon_charge[1]')\
         .Define('Dimuon_mass', 'InvariantMass(Muon_pt, Muon_eta, Muon_phi, Muon_mass)')\
         .Filter('Dimuon_mass > 70')\
         .Range(1000)
  
  # Trigger the event loop by asking for the mean of the dimuon mass.
  print('\nApproximate mass of the Z boson: {:.2f} GeV\n'.format(
      df.Mean('Dimuon_mass').GetValue()))
  
  # Describe again the state of the dataframe.
  print(df.Describe())
  
subject: Add tutorial for Describe