sS joinAdjacentTokensIf(S s, IF2 pred) { LS tok = javaTok(s); new LS out; for (int i = 3; i < l(tok); i += 2) if (nempty(tok.get(i-1)) && pred.get(tok.get(i-2), tok.get(i))) tok.set(i-1, ""); ret join(tok); }