public static TTFSequenceMessage TTFSequenceMessageFrom(
      SequenceOperation opt, int rep, VectorClock vc) {
    TTFOperation op;
    if (opt.getType() == OpType.insert) {
      op = new TTFOperationWithId(opt.getType(), opt.getPosition(), opt.getContent().get(0), rep);
    } else {
      op = new TTFOperationWithId(opt.getType(), opt.getPosition(), null, rep);
    }

    OTMessage smess = new OTMessage(vc, rep, op);
    TTFSequenceMessage mess = new TTFSequenceMessage(smess);
    return mess;
  }
 private static SequenceOperation delete(int p, int o) {
   return SequenceOperation.delete(p, o);
 }
 // helpers
 private static SequenceOperation insert(int p, String s) {
   return SequenceOperation.insert(p, s);
 }