void df008_createDataSetFromScratch()
{
   // We create an empty data frame of 100 entries
   ROOT::RDataFrame df(100);

   // We now fill it with random numbers
   gRandom->SetSeed(1);
   auto df_1 = df.Define("rnd", []() { return gRandom->Gaus(); });

   // And we write out the dataset on disk
   df_1.Snapshot("randomNumbers", "df008_createDataSetFromScratch.root");
}