prd_nameOrSeqmark :: NAME_OR_SEQMARK -> Set.Set NAME
prd_nameOrSeqmark nos =
    case nos of
         Name n -> prd_name n
         SeqMark s -> prd_seqmark s
prd_nameOrSeqmark :: NAME_OR_SEQMARK -> Set.Set NAME
prd_nameOrSeqmark nos =
    case nos of
         Name n -> prd_name n
         SeqMark s -> prd_seqmark s
prd_nameOrSeqmark nos =
    case nos of
         Name n -> prd_name n
         SeqMark s -> prd_seqmark s