static SuffixTree_managed loadOnDiskSuffixTree(File treeFile, File textFile) {
  bool toUpper = true;
  CloseableCharSequence text = iso8859_readOnlyFileAsCharSequence(textFile, noToString := true);
  if (toUpper) text = virtualToUpper(text);
  print(l(text));
  IIntMemory mem = ROMIntMemoryFromFile(treeFile);
  print(mem.size());
  SuffixTree_managed tree = new(mem, 1);
  tree.fullText = text;
  tree.dependentCloseables = ll(text, optCast AutoCloseable(mem));
  ret tree;
}