old_contents: import unittest
  import ROOT
  
  class HistogramsFromTDF(unittest.TestCase):
      @classmethod
      def setUp(cls):
          ROOT.gRandom.SetSeed(1)
  
      def test_histo1D(self):
      	ROOT.gRandom.SetSeed(1)
      	tdf = ROOT.ROOT.Experimental.TDataFrame(64)
      	g = tdf.Define("r","gRandom->Gaus(0,1)")
      	h1Proxy = g.Histo1D(("h1","h1",64, -2., 2.),"r")
      	h1 = h1Proxy.GetValue()
  
          cppCode = 'gRandom->SetSeed(1);' + \
                    'ROOT::Experimental::TDataFrame tdf(64);' + \
                    'auto g = tdf.Define("r","gRandom->Gaus(0,1)");' + \
                    'auto h2Proxy = g.Histo1D({"h1","h1",64, -2., 2.},"r");'
          ROOT.gInterpreter.ProcessLine(cppCode)
          h2 = ROOT.h2Proxy.GetValue()
  
          self.assertEqual(h1.GetEntries(), h2.GetEntries())
          self.assertEqual(h1.GetMean(), h2.GetMean())
          self.assertEqual(h1.GetStdDev(), h2.GetStdDev())
  
  if __name__ == '__main__':
      unittest.main()
new_contents: import unittest
  import ROOT
  
  class HistogramsFromTDF(unittest.TestCase):
      @classmethod
      def setUp(cls):
          ROOT.gRandom.SetSeed(1)
  
      def test_histo1D(self):
          ROOT.gRandom.SetSeed(1)
          tdf = ROOT.ROOT.Experimental.TDataFrame(64)
          g = tdf.Define("r","gRandom->Gaus(0,1)")
          h1Proxy = g.Histo1D(("h1","h1",64, -2., 2.),"r")
          h1 = h1Proxy.GetValue()
  
          cppCode = 'gRandom->SetSeed(1);' + \
                    'ROOT::Experimental::TDataFrame tdf(64);' + \
                    'auto g = tdf.Define("r","gRandom->Gaus(0,1)");' + \
                    'auto h2Proxy = g.Histo1D({"h1","h1",64, -2., 2.},"r");'
          ROOT.gInterpreter.ProcessLine(cppCode)
          h2 = ROOT.h2Proxy.GetValue()
  
          self.assertEqual(h1.GetEntries(), h2.GetEntries())
          self.assertEqual(h1.GetMean(), h2.GetMean())
          self.assertEqual(h1.GetStdDev(), h2.GetStdDev())
  
  if __name__ == '__main__':
      unittest.main()
  
subject: Replace tabs with spaces in the unit tests.