File conversion from .root to .lhe

[Wile_E_Coyote]

Some ideas:

• various HepMC3 → examples
• HepMC3 → examples → ConvertExample (note: the WriterLHEF class does not exist)
• HepMC3 → examples → LHEFExample (HepMC3 → include/HepMC3/LHEF.h and HepMC3 → include/HepMC3/LHEFAttributes.h for manipulation with the LHEF events)

Hepmc file to .root conversion

# note: ROOTSYS must be set in advance, and below, use the same # Python version as returned by: root-config --python-version # (for me, it's Python 3.10.4, hence 3.10 and 310 below) rm -rf HepMC3 HepMC3-build HepMC3-install # a total cleanup git clone --depth=1 https://gitlab.cern.ch/hepmc/HepMC3 mkdir HepMC3-build cd HepMC3-build cmake -DCMAKE_INSTALL_PREFIX=../HepMC3-install \ -DHEPMC3_PYTHON_VERSIONS=3.10 \ -DHEPMC3_Python_SITEARCH310=../HepMC3-install/lib/python3.10…