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, "$X");
  if (position < 0) fail("bad");
  if (ai_useThoughtSpaces()) {
    AbstractThoughtSpace ts = thoughtSpace();
    ret ai_tripleRefsToTexts(a, b, c, ai_thoughtSpace_query(a, b, c, ts));
  }
  
  ret allToSymbol(web_texts(ai_search_dollarX(a, b, c)));
}