private StatementTreeImpl translateStat(final Statement stat) {
    if (stat == null) {
      return null;
    }

    curStat = null;
    stat.accept(this);
    assert curStat != null : "null for " + stat;
    return curStat;
  }
 private List<? extends StatementTree> translateStats(final List<? extends Statement> stats) {
   if (stats == null) {
     return null;
   }
   final List<StatementTreeImpl> statTrees = new ArrayList<>(stats.size());
   for (final Statement stat : stats) {
     curStat = null;
     stat.accept(this);
     assert curStat != null;
     statTrees.add(curStat);
   }
   return statTrees;
 }