// i = index of "implements"/"extends"
static int tok_endOfImplementsList(L<S> tok, int i) {
  int level = 0;
  while (i < l(tok)) {
    S t = tok.get(i);
    if (eq(t, "<")) ++level;
    else if (eq(t, ">")) {
      if (level == 0) ret i; else --level;
    } else if (eq(t, "{")) ret i;
    i += 2;
  }
  ret i;
}