static L<Symbol> ai_texts(CharSequence _a, CharSequence _b, CharSequence _c) {
  Symbol a = symbol(_a), b = symbol(_b), c = symbol(_c);
  int position = tripleIndexOf(a, b, c, symbol_dollarX());
  if (position < 0) fail("No $X in " + ai_renderTriple(a, b, c));
  if (ai_useThoughtSpaces())
    ret ai_texts(a, b, c, thoughtSpace());

  // legacy  
  ret allToSymbol(web_texts(ai_search_dollarX(a, b, c)));
}

static L<Symbol> ai_texts(Symbol a, Symbol b, Symbol c, AbstractThoughtSpace ts) {
  ret ai_tripleRefsToTexts(a, b, c, ai_thoughtSpace_query(a, b, c, ts));
}

static L<Symbol> ai_texts(T3<Sym> t) {
  ret t == null ? sharedEmptyList() : ai_texts(t.a, t.b, t.c);
}