code: def sort_nts(self, nt_list, codekey):
          
          # Problem is that some members in the nt_list do NOT have
          # codekey=EvidenceCode, then it returns None, which breaks py34 and 35
          # The fix here is that for these members, default to -1 (is this valid?)
          sortby = lambda nt: self.ev2idx.get(getattr(nt, codekey), -1)
          return sorted(nt_list, key=sortby)
docs: Sort list of namedtuples such so evidence codes in same order as code2nt.