void df000_simple()
{
   // Create a data frame with 100 rows
   ROOT::RDataFrame rdf(100);

   // Define a new column `x` that contains random numbers
   auto rdf_x = rdf.Define("x", [](){ return gRandom->Rndm(); });

   // Create a histogram from `x`
   auto h = rdf_x.Histo1D("x");

   // At the end of this function, the histogram pointed to by `h` will be deleted.
   // Draw a copy of the histogram object instead:
   h->DrawClone();
}