// func returns S[] {beg, end}
static L<S> replaceKeywordBlockDyn(L<S> tok, S keyword, O func) {
  for (int i = 0; i < 1000; i++) {
    int idx = findCodeTokens(tok, keyword, "{");
    if (idx < 0)
      break;
    int j = findEndOfBracketPart(tok, idx+2);
    
    S[] be = (S[]) callF(func);
    tok.set(idx, be[0]);
    tok.set(idx+1, " ");
    tok.set(idx+2, "");
    tok.set(j-1, be[1]);
    reTok(tok, idx, j);
  }
  ret tok;
}

Began life as a copy of #1001885