static LPair<S> directlyAdjacentWords(S s) {
  LS tok = javaTokC(s);
  LPair<S> out = new L;
  for (int i = 0; i+1 < l(tok); i++)
    if (isIdentifier(tok.get(i)) && isIdentifier(tok.get(i+1)))
      out.add(pair(tok.get(i), tok.get(i+1)));
  ret out;
}