static L<TripleWeb> ai_fillTripleIndex_useThese;
static O ai_fillTripleIndex_useTripleIndex;

static void ai_fillTripleIndex() {
  if (ai_fillTripleIndex_useTripleIndex != null) {
    print("Copying triple index.");
    ai_reuseTripleIndex(ai_fillTripleIndex_useTripleIndex);
    ai_fillTripleIndex_useTripleIndex = null;
    ai_fillTripleIndex_useThese = null;
    ret;
  }
  
  print("Getting triples.");
  time2 {
    L<TripleWeb> triples = ai_fillTripleIndex_useThese != null
      ? ai_fillTripleIndex_useThese
      : localSoftwareMadeTriples();
    ai_fillTripleIndex_useThese = null;
  }
  long time = lastTiming();
  long us = ratio(time*1000, l(triples));
  //print("Got triples in "T + time + " ms. Making triple index of " + nTriples(triples) + ".");
  print("Got " + nTriples(triples) + " in " + us + " "+ unicode_micro() + "s per triple. Making triple index.");
  time "Triple index made." {
    ai_replaceTripleIndexWithTriples(triples);
    //ai_tripleIndexToInvalidatedWebs();
    ai_deleteInvalidTriples();
  }
}

Began life as a copy of #1010532