Example showing easy HepMC extraction using GeneratorPythia8

This example demonstrates how we can extend GeneratorPythia8 in a user-defined macro (or external generator), to achieve additional HepMC3 export of generated Pythia8 events.

The example provides a small utility for poeple in need to obtain HepMC files from Pythia8. Note that many other methods to achieve this are possible (See original Pythia8 example).

The example provides:

• The external generator implementation Pythia8HepMC3.C
• a run.sh script demonstrating it's usage and a check feeding back the generated hepmc into the simulation