sS nlLogic_applySimplePhraseReplacementRule(S s, IfThen rule) {
  S in = nlLogic_funcArgText(rule.in, 'phrase);
  if (in == null) ret s;
  S out = nlLogic_funcArgText(rule.out, 'phrase);
  if (out == null) ret s;
  ret replacePhrase(s, in, out);
}