code: def lookup_cc_partner(nu_pid):
      
  
      neutrino_type = math.fabs(nu_pid)
      assert neutrino_type in [12, 14, 16]
  
      cc_partner = neutrino_type - 1  # get e, mu, tau
      cc_partner = math.copysign(
          cc_partner, nu_pid)  # make sure matter/antimatter
      cc_partner = int(cc_partner)  # convert to int
  
      return cc_partner
docs: Lookup the charge current partner
  
      Takes as an input neutrino nu_pid is a PDG code, then returns
      the charged lepton partner.  So 12 (nu_e) returns 11.  Keeps sign