code: def update_cnum(self):
          
          if "ConferencePaper" not in self.collections:
              cnums = record_get_field_values(self.record, '773', code="w")
              for cnum in cnums:
                  cnum_subs = [
                      ("9", "INSPIRE-CNUM"),
                      ("a", cnum)
                  ]
                  record_add_field(self.record, "035", subfields=cnum_subs)
docs: Check if we shall add cnum in 035.